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Biomedical subjects

Kaoru Inoue

Publications and source records attributed to Kaoru Inoue.

At least 19 recordsLinked to original sources

Effects of vertically transferred 3,3',4,4',5-pentachlorobiphenyl (PCB-126) on the reproductive development of female rats.

In order to study the effects of vertically transferred coplanar polychlorinated biphenyls on female reproductive development, female rat offspring from dams of Sprague-Dawley strain, which received daily oral administration of vehicle (corn oil) or 1 or 3 microg/kg of 3,3',4,4',5-pentachlorobiphenyl (PCB-126) from 2 weeks prior to mating with intact males until 20 days after delivery were examined from birth until puberty. Hepatic expression of the aryl hydrocarbon receptor (AhR)-inducible enzyme cytochrome P450 1A1 (CYP1A1) was detected in all offspring from PCB-126-exposed dams, indicating vertical transfer of PCB-126. Furthermore, quantification of ovarian mRNAs encoding CYP1A1, AhR and ARNT demonstrated that the ovary equipped the AhR-signaling system through which transcription of the CYP1A1 gene was enhanced in a dose-dependent manner. Exposure to PCB-126 retarded the growth of offspring in both exposed groups, while the viability of the neonates of the exposed groups was comparable to that of the oil-exposed controls. The exposure to 3 mug/kg/day reduced the ovarian weight on postnatal day (PND) 24, with atresia of most of the antral follicles and delayed vaginal opening. Exposure to 1 microg/kg/day did not produce such effects; however, both doses of PCB-126 induced external urogenital anomalies, such as vaginal thread and hypospadias, in all of the PCB-126-exposed female offspring. These results indicate that vertically transferred PCB-126 is potent enough to exert a direct effect on the ovary and adversely affect female puberty by altering the morphological and functional development of the female reproductive system.

Animals↗

Cohesin protein SMC1 represses the nuclear receptor CAR-mediated synergistic activation of a human P450 gene by xenobiotics.

CAR (constitutive active/androstane receptor) regulates both the distal enhancer PBREM (phenobarbital-responsive enhancer module) and the proximal element OARE [OA (okadaic acid) response element] to synergistically up-regulate the endogenous CYP2B6 (where CYP is cytochrome P450) gene in HepG2 cells. In this up-regulation, CAR acts as both a transcription factor and a co-regulator, directly binding to and enhancing PBREM upon activation by xenobiotics such as TCPOBOP {1,4-bis-[2-(3,5-dichloropyridyloxy)]benzene} and indirectly associating with the OARE in response to OA [Swales, Kakizaki, Yamamoto, Inoue, Kobayashi and Negishi (2005) J. Biol. Chem. 280, 3458-3466]. We have now identified the cohesin protein SMC1 (structural maintenance of chromosomes 1) as a CAR-binding protein and characterized it as a negative regulator of OARE activity, thus repressing synergy. Treatment with SMC1 small interfering RNA augmented the synergistic up-regulation of CYP2B6 expression 20-fold in HepG2 cells, while transient co-expression of spliced form of SMC1 abrogated the synergistic activation of a 1.8 kb CYP2B6 promoter. SMC1 indirectly binds to a 19 bp sequence (-236/-217) immediately downstream from the OARE in the CYP2B6 promoter. Both DNA affinity and chromatin immunoprecipitation assays showed that OA treatment dissociates SMC1 from the CYP2B6 promoter, reciprocating the indirect binding of CAR to OARE. These results are consistent with the conclusion that SMC1 binding represses OARE activity and its dissociation allows the recruitment of CAR to the OARE, synergizing PBREM activity and the expression of the CYP2B6 gene.

Animals↗

A repeated 28-day oral dose toxicity study of nonylphenol in rats, based on the 'Enhanced OECD Test Guideline 407' for screening of endocrine-disrupting chemicals.

A 28-day repeated oral dose toxicity study of nonylphenol (NP) was performed for an international validation of the 'Enhanced OECD Test Guideline 407' paying particular attention to the sensitivity of individual endocrine-related parameters. Sprague-Dawley rats, each group consisting of ten males and ten females, were administered NP once daily by gavage at doses of 0 (control), 10, 50, or 250 mg/kg body weight. At 250 mg/kg, three females died or became moribund during the experiment. At this dose, hepatic and renal toxicity was evident in both sexes with increase of relative liver and kidney weights as well as histopathological changes, such as centrilobular liver cell hypertrophy and a variety of renal tubular lesions, and alteration of serum biochemical parameters, some of them being evident from 50 mg/kg in females (glucose and inorganic phosphates). Hematologically, development of anemia was evident at 250 mg/kg in both sexes. Regarding endocrine-related effects, increase of thyroid weight in males was detected from 50 mg/kg. At 250 mg/kg, males exhibited reduction of relative weights of the ventral prostate and seminal vesicles, and females developed irregular estrous cyclicity and vaginal mucosal hyperplasia. Although changes in serum hormone levels were detected in both sexes, magnitude of the changes was small to be regarded as a low toxicological significance. In summary, repeated oral doses of NP to rats for 28 days resulted in hepato-renal toxicity from 50 mg/kg and anemia at 250 mg/kg. Effects on the endocrine system were observed from 50 mg/kg, and assessment of weights and histopathology of endocrine-related organs and estrous cyclicity may be valid in a battery for detecting endocrine effects of NP. The no-observed-adverse-effect level of NP was estimated to be 10 mg/kg per day.

Administration, Oral↗

New approach to in situ quantification of ovarian gene expression in rat using a laser microdissection technique: relationship between follicle types and regulation of inhibin-alpha and cytochrome P450aromatase genes in the rat ovary.

The recently developed laser microdissection (LMD) technique makes it possible to quantify local gene expression in the target cells of various tissues. Using the LMD technique, this study aimed at comparing the amounts of mRNAs encoding the inhibin-alpha subunit and cytochrome P450 aromatase (P450(arom)) in granulosa cells between preantral and antral follicles in immature rat ovaries. Serial frozen sections of the ovaries from 24-day-old female Wistar rats were made and 30 healthy preantral (100-200 microm maximum diameter) and ten healthy antral ( > 300 microm maximum diameter) follicles were selected in each ovary based on morphological examinations, including immunohistochemistry for inhibin-alpha, in sections adjacent to those used for LMD. The amounts of mRNAs encoding inhibin-alpha subunit and P450(arom) were quantified by real-time polymerase chain reaction (PCR). While the amount of P450(arom) mRNA in the granulosa cell layers from the antral follicles was about 12-times higher than that in the preantral follicles, no difference in the amount of inhibin-alpha mRNA was found between these two types of follicles. Thus, the LMD technique allowed the in situ quantification of gene expression in the ovary and revealed that each granulosa cell expresses a stable amount of inhibin-alpha subunit mRNA independently of antral formation in immature rat ovaries.

Animals↗

Subchronic toxicity study of water pepper extract in F344 rats.

A subchronic toxicity study of water pepper extract (WPE) from Polygonum hydropiper L. was conducted in groups of 10 male and 10 female F344 rats fed powdered diets containing 0, 62.5, 250, 1000 or 4000 ppm concentrations for 13 weeks. Suppression of body weight gain due to decreased food consumption was observed in both sexes at 4000 ppm, and at autopsy, increase of relative weights was observed for the brain, liver, spleen, kidneys, and testes in these animals, suggestive of the reflection of the reduced body weights. At this dose, slight increases of blood urea nitrogen in both sexes and serum alanine aminotransferase, Na and Cl in females, were observed, suggestive of weak hepatic and renal toxicity, at least in females. The same females also exhibited slight decrease of red blood cells and haematocrit, slight increase of mean corpuscular volume and mean corpuscular haemoglobin, and minimal increase of splenic haemosiderin deposition, providing evidence of slight haemolytic anemia. On the other hand, enhanced accumulation of mast cells was observed in the mesenteric lymph nodes at 4000 ppm in males and 1000 and 4000 ppm in females. Considering the anti-anaphylactic properties of polygodial, a major constituent of WPE, the mast cell accumulation was concluded to be an adaptive change in response to the subchronic oral administration of WPE. Based on the present toxicity data, 1000 ppm was determined to be the no-observed-adverse-effect level, translating into 57.4 and 62.9 mg/kg/day for male and female rats, respectively.

Animals↗

Methacarn fixation--effects of tissue processing and storage conditions on detection of mRNAs and proteins in paraffin-embedded tissues.

In this study, we examined suitable conditions for tissue fixation with methacarn and ethanol dehydration and storage of paraffin-embedded tissues (PETs) on gene expression analysis. With fixation and dehydration of rat liver tissues for up to 16 h (overnight) and 1 week, respectively, at 4 degrees C, integrity of extracted total RNAs and polypeptides did not vary, the former integrity being constantly lower than that with unfixed frozen tissue, while protein yield was slightly reduced with increasing dehydration. Retained expression levels of mRNAs and proteins were mostly unaffected by the period of fixation but slightly fluctuated with the length of dehydration. When PETs were stored for up to 12 months, integrity of both total RNAs and polypeptides was retained at 4 degrees C but reduced at room temperature. Reduced expression levels of mRNAs and proteins were also noted by storage at room temperature after 12 and 3 months, respectively. However, neither tissue processing nor storage affected variability in either mRNA or protein levels among samples. Thus, the results suggest that, for gene expression analysis, tissues can be fixed with methacarn and dehydrated for at least 1 day and 1 week, respectively, and PETs can be stored for at least 12 months, but a temperature of 4 degrees C is preferable.

Acetic Acid↗

A case report of a spontaneous gastrointestinal stromal tumor (GIST) occurring in a F344 rat.

We report a case of gastrointestinal stromal tumor (GIST) that developed in a male F344 rat at week 101 of an experiment in a carcinogenicity study. Macroscopically, the primary tumor, which measured 1 cm in diameter, involved the submucosal tissue of the forestomach at the lesser curvature extending to the glandular stomach and esophagus. Histopathologically, the tumor was composed of neoplastic cells with small- to medium-sized spindle-shaped single nuclei and fibrillary cytoplasm lacking distinct cell borders. It invaded extensively into the tunica muscularis and subserosa, further extending to the lamina propria mucosa and serosal surface. A few densely proliferating portions showed a tendency to storiform pattern. Metastatic tumor nodules were found in the liver, spleen, and femur bone marrow, with multiple nodules, up to 1 cm in diameter, apparent in the liver. Immunohistochemically, diffuse, but weak cytoplasmic immunoreactivity for KIT was evident, and most neoplastic cells also exhibited strong immunoreactivity for a -smooth muscle actin and vimentin. Sparse nuclear S-100-immunoreactive cells were further observed, but none of neoplastic cells were immunoreactive for CD34, caldesmon, desmin, cytokeratin, or synaptophysin. Collectively, these features meet the criteria for a GIST, with limited potential for differentiation to smooth muscle and neural cells.

Actins↗

Impact of maternal dietary exposure to endocrine-acting chemicals on progesterone receptor expression in microdissected hypothalamic medial preoptic areas of rat offspring.

We have previously examined the impact of perinatal exposure to ethinylestradiol (EE), methoxychlor (MXC), diisononyl phthalate (DINP), and genistein (GEN) in maternal diet on rat offspring, and found developmental and/or reproductive toxicity with 0.5 ppm EE, 1200 ppm MXC, and 20,000 ppm DINP. Although the toxicological profile with MXC was similar to the EE case, the population changes in pituitary hormone-producing cells totally differed between the two cases, changes being evident from 240 ppm with MXC. In the present study, to assess the impact of these agents on brain sexual differentiation, region-specific mRNA expression of estrogen receptors (ER) alpha and beta, the progesterone receptor (PR), gonadotrophin-releasing hormone, steroid receptor coactivators (SRC)-1 and -2, and calbindin-D in microdissected hypothalamic medial preoptic areas (MPOAs) at postnatal day 10 was first analyzed in rats exposed to 0.5 ppm-EE from gestational day 15 by real-time RT-PCR. Sexually dimorphic expression of ER alpha and PR was noted with predominance in females and males, respectively, EE up-regulating SRC-1 in males and ER beta and PR in females. Next, we similarly examined expression changes of ER alpha and beta, PR, and SRC-1 in animals exposed to MXC at 24, 240, and 1200 ppm, DINP at 4000 and 20,000 ppm, and GEN at 1000 ppm. MXC at 1200 ppm down- and up-regulated PR in males and females, respectively, and DINP at 20,000 ppm down-regulated PR in females, while GEN did not exert any clear effects. The results thus suggest that agents causing developmental and/or reproductive abnormalities in later life may affect hypothalamic PR expression during the exposure period in early life.

Animals↗

Chemoprevention of acrylamide toxicity by antioxidative agents in rats--effective suppression of testicular toxicity by phenylethyl isothiocyanate.

The efficacies of N-acetylcysteine (NAC), phenylethyl isothiocyanate (PEITC), and 1-O-hexyl-2,3,5-trimethylhydroquinone (HTHQ) at preventing the neurotoxicity and testicular toxicity of acrylamide (ACR) were investigated in rats. To this end, Sprague-Dawley males were given 0.02% ACR in drinking water, with or without 1% NAC, 0.5% PEITC or 0.1% HTHQ in the diet for four weeks. A group of untreated controls was also included in the study. All ACR-treated animals exhibited progressive neurotoxicity as judged by gait scores, and among the chemicals co-administered, only HTHQ caused any suppression by the end of the experiment, and this was slight. The severity of the neurotoxicity, as judged by axonal degeneration in the spinal gracile fasciculus and sciatic nerve (distal portion) and aberrant dot-like synaptophysin immunoreactivity, reflecting nerve terminal degeneration in the cerebellar molecular layer, was not clearly reduced by co-administration of HTHQ, NAC or PEITC either. ACR-induced sciatic nerve axon atrophy was marginally and non-significantly reduced by HTHQ. In contrast, in terms of ACR-induced testicular toxicity, exfoliation of spermatids into seminiferous lumen was clearly reduced by co-administered PEITC and was marginally reduced by co-administered HTHQ. These antioxidative agents may therefore reduce/prevent ACR-induced toxicity, at least in the testes.

Acrylamide↗

Limited tumor-initiating activity of phenylethyl isothiocyanate by promotion with sodium L-ascorbate in a rat two-stage urinary bladder carcinogenesis model.

Initiation activity of phenylethyl isothiocyanate (PEITC) was examined in a two-stage urinary bladder carcinogenesis model. Male 6-week-old Fischer 344 rats were fed diet containing 0.1% PEITC for 12 or 24 weeks, with or without subsequent administration of 5% sodium l-ascorbate (Na-AsA) in diet until week 48, or for the entire experimental period. After 12 weeks of PEITC-treatment, both simple hyperplasia and papillary or nodular (PN) hyperplasia had developed in all animals, but the majority of these lesions had disappeared at week 48, irrespective of the Na-AsA-treatment. The same lesions after 24 weeks of PEITC-treatment had progressed to dysplasia and carcinoma, in a small number of cases by week 48 (6% in incidence for each lesion), but enhancement by the Na-AsA-treatment was evident only with simple hyperplasias (from 56 to 100% in incidence) and PN hyperplasias (from 19 to 56%). The results suggest a limited initiation activity of PEITC with induction of irreversible lesions by 24 weeks of exposure.

Animals↗

Protective movements during sideways falls from standing height.

To examine the effect of protective movements during sideways falls from standing height (i.e., from the standing position), a two-step study was performed. In the first step, 80 young male and female volunteers freely fell onto a sport-mat. All falls were recorded on videotape, and replayed to analyze movements in response to the falls. Several protective movements were observed; forward flexion and lateral flexion were observed with a particularly high frequency. In the second step, impact velocities of the head and hip were measured by a three-dimensional motion analyzer regarding three types of falls: stiff falls, forward flexion falls and lateral flexion falls. Both types of flexion reduced impact velocities of the head, but not those of the hip. The reduction of the impact velocity on the head correlated with the lowering of the height of the head from the floor.

Accidental Falls↗

Novel CAR-mediated mechanism for synergistic activation of two distinct elements within the human cytochrome P450 2B6 gene in HepG2 cells.

The constitutive active receptor (CAR) regulates the induction of the cytochrome P450 2B6 (CYP2B6) gene by phenobarbital-type inducers, such as 1,4 bis[2-(3,5-dichloropyridyloxy)]benzene (TCPOBOP) via the distal phenobarbital-responsive enhancer module (PBREM, at -1732/-1685 bp). Activation of the PBREM by TCPOBOP generated a 10-fold induction of CYP2B6 mRNA in HepG2 cells stably expressing mouse CAR (Ym17). Co-treatment with the protein phosphatase inhibitor okadaic acid (OA) synergistically increased this induction over 100-fold without directly activating CAR or the PBREM. Although OA synergy required the presence of PBREM, deletion assays delineated the OA-responsive activity to a proximal 24-bp (-256/-233) sequence (OARE) in the CYP2B6 promoter. CAR did not directly bind to the OARE in electrophoretic mobility shift assays. However, both DNA affinity and chromatin immunoprecipitation assays showed a significant increase in CAR association with the OARE after co-treatment with TCPOBOP and OA, indicating the indirect binding of CAR to the OARE. The two cis-acting elements, the distal PBREM and the proximal OARE, within the chromatin structure are both regulated by CAR in response to TCPOBOP and OA, respectively, to maximally induce the CYP2B6 promoter. This functional interaction between the two sites expands the current understanding of the mechanism of CAR-mediated inducible transcription.

Aryl Hydrocarbon Hydroxylases↗

Molecular characterization of binding subcomponents of Clostridium botulinum type C progenitor toxin for intestinal epithelial cells and erythrocytes.

Clostridium botulinum type C 16S progenitor toxin consists of a neurotoxin (NTX), a non-toxic non-HA (NTNH), and a haemagglutinin (HA). The HA acts as an adhesin, allowing the 16S toxin to bind to intestinal epithelial cells and erythrocytes. In type C, these bindings are dependent on sialic acid. The HA consists of four distinct subcomponents designated HA1, HA2, HA3a and HA3b. To identify the binding subcomponent(s) of HA of type C 16S toxin, all of the HA-subcomponents and some of their precursor forms were produced as recombinant proteins fused to glutathione S-transferase (GST). These proteins were evaluated for their capacity to adhere to intestinal epithelial cells of guinea pig and human erythrocytes. GST-HA1, GST-HA3b and GST-HA3 (a precursor form of HA3a and HA3b) bound intestinal epithelial cells and erythrocytes, whereas GST alone, GST-HA2 and GST-HA3a did not. GST-HA3b and GST-HA3 showed neuraminidase-sensitive binding to the intestinal epithelial cells and erythrocytes, whereas GST-HA1 showed neuraminidase-insensitive binding. TLC binding assay revealed that GST-HA3b and GST-HA3 recognized sialosylparagloboside (SPG) and GM3 in the ganglioside fraction of the erythrocytes, like native type C 16S toxin [Inoue, K. et al. (1999). Microbiology 145, 2533-2542]. On the other hand, GST-HA1 recognized paragloboside (PG; an asialo- derivative of SPG) in addition to SPG and GM3. Deletion mutant analyses of GST-HA3b showed that the C-terminal region of HA3b is important for its binding activity. Based on these data, it is concluded that the HA component contains two distinct carbohydrate-binding subcomponents, HA1 and HA3b, which recognize carbohydrates in different specificities.

Amino Acid Sequence↗

Structural analysis by X-ray crystallography and calorimetry of a haemagglutinin component (HA1) of the progenitor toxin from Clostridium botulinum.

Botulism food poisoning is caused primarily by ingestion of the Clostridium botulinum neurotoxin (BoNT). The 1300 amino acid BoNT forms a progenitor toxin (PTX) that, when associated with a number of other proteins, increases its oral toxicity by protecting it from the low pH of the stomach and from intestinal proteases. One of these associated proteins, HA1, has also been suggested to be involved with internalization of the toxin into the bloodstream by binding to oligosaccharides lining the intestine. Here is reported the crystal structure of HA1 from type C Clostridium botulinum at a resolution of 1.7 Angstrom. The protein consists of two beta-trefoil domains and bears structural similarities to the lectin B-chain from the deadly plant toxin ricin. Based on structural comparison to the ricin B-chain lactose-binding sites, residues of type A HA1 were selected and mutated. The D263A and N285A mutants lost the ability to bind carbohydrates containing galactose moieties, implicating these residues in carbohydrate binding.

Amino Acid Sequence↗

Cytoplasmic accumulation of the nuclear receptor CAR by a tetratricopeptide repeat protein in HepG2 cells.

The nuclear constitutive active receptor (CAR) is a key transcription factor regulating phenobarbital (PB)-inducible transcription of various hepatic genes that encode xenobiotic/steroid-metabolizing enzymes. CAR is retained in the cytoplasm of noninduced livers and translocates into the nucleus after PB induction. HepG2 cells lack the capability of retaining CAR in the cytoplasm; thus, the receptor spontaneously accumulates in the nucleus. We have now cloned and characterized a tetratricopeptide repeat (TPR) protein, designated cytoplasmic CAR retention protein (CCRP), for its ability to accumulate the receptor in the cytoplasm of cotransfected HepG2 cells. CCRP directly interacts with the ligand-binding domain of CAR and mediates the formation of a cytoplasmic CAR-CCRP-90-kDa heat shock protein (hsp90) ternary complex. Simultaneous expression of fluorescent protein-tagged CAR and CCRP reveals their colocalization with tubulin in mouse liver in vivo. Thus, these results indicate that CCRP may be a component of the CAR-hsp90 complex and involved in retaining the receptor in the cytoplasm of both HepG2 cells and probably in vivo liver cells.

Animals↗

Purification of fully activated Clostridium botulinum serotype B toxin for treatment of patients with dystonia.

Clostridium botulinum serotype B toxins 12S and 16S were separated by using a beta-lactose gel column at pH 6.0; toxin 12S passed through the column, whereas toxin 16S bound to the column and eluted with lactose. The fully activated neurotoxin was obtained by applying the trypsin-treated 16S toxin on the same column at pH 8.0; the neurotoxin passed through the column, whereas remaining nontoxic components bound to the column. The toxicity of this purified fully activated neurotoxin was retained for a long period by addition of albumin in the preparation.

Amino Acid Sequence↗

Detection of gene expression of vascular endothelial growth factor and flk-1 in the renal glomeruli of the normal rat kidney using the laser microdissection system.

The recent development of the laser microdissection (LMD) technique enables one to target particular tissues or cells for gene or protein analyses. The purpose of this study was to detect local mRNA expression of vascular endothelial growth factor (VEGF) and its receptor, flk-1, in the glomeruli of normal rat kidneys using the LMD system. Frozen sections of the kidney of 8-week-old male Wistar rats were made. The glomeruli were dissected from the frozen sections with the LMD system, and total RNA was extracted from 200 glomeruli in each kidney. Reverse-transcription polymerase chain reaction (RT-PCR) revealed the local mRNA expression of three isoforms of VEGF, flk-1 and GAPDH in the glomeruli. Moreover, the real-time PCR was performed to evaluate the experimental condition for quantification of VEGF and flk-1 mRNA expression using this system, and the results showed that at least 10 glomeruli might be needed for quantifying local VEGF mRNA expression. However, cDNA from 200 glomeruli was not enough for quantitative evaluation of flk-1 mRNA with this system. These results demonstrate the reproducibility of the analysis of mRNA expression in the renal glomeruli using the LMD system and also suggest that the application of the LMD technique will provide information to further our understanding of the mechanisms involved in kidney diseases.

Angiogenesis Inducing Agents↗

Prevalent involvement of illegitimate V(D)J recombination in chromosome 9p21 deletions in lymphoid leukemia.

To understand molecular pathways underlying 9p21 deletions, which lead to inactivation of the p16/CDKN2A, p14/ARF, and/or p15/CDKN2B genes, in lymphoid leukemia, 30 breakpoints were cloned from 15 lymphoid leukemia cell lines. Seventeen (57%) breakpoints were mapped at five breakpoint cluster sites, BCS-LL1 to LL5, each of <15 bp. Two breakpoint cluster sites were located within the ARF and CDKN2B loci, respectively, whereas the remaining three were located >100 kb distal to the CDKN2A, ARF, and CDKN2B loci. The sequences of breakpoint junctions indicated that deletions in the 11 (73%) cell lines were mediated by illegitimate V(D)J recombination targeted at the five BCS-LL and six other sites, which contain sequences similar to recombination signal sequences for V(D)J recombination. An extrachromosomal V(D)J recombination assay indicated that BCS-LL3, at which the largest number of breakpoints (i.e. five breakpoints) was clustered, has a V(D)J recombination potential 150-fold less than the consensus recombination signal sequence. Three other BCS-LLs tested also showed V(D)J recombination potential, although it was lower than that of BCS-LL3. These results indicated that illegitimate V(D)J recombination, which was targeted at several ectopic recombination signal sequences widely distributed in 9p21, caused a large fraction of 9p21 deletions in lymphoid leukemia.

Base Sequence↗