The G1-phase cell-cycle inhibitor p21 has been proposed to mediate growth arrest during differentiation. Upregulation of p21 has been shown in multiple cell lines induced to differentiate; however, the mechanism of p21 induction during normal differentiation is largely unknown. In this report, we use normal hematopoietic precursor cells obtained from umbilical cord to model p21 regulation durin...

BACKGROUND Although p21 is an important component that regulates cell-cycle progression, no consensus has been reached about its clinicopathological significance in esophageal squamous cell carcinoma (ESCC). In the present study, we investigated its prognostic significance and correlation with cyclin-D1 (CCND1) expression in ESCC. MATERIALS AND METHODS The p21 labeling index (LI) was calculat...

rho GDP dissociation inhibitor (GDI) is an inhibitory GDP/GTP exchange protein for a group of small GTP-binding proteins including at least rhoA p21, rhoB p21, rac1 p21, rac2 p21, and G25K. Microinjection of rho GDI into Swiss 3T3 cells made the cells round and refractile. This morphological change was accompanied by the disappearance of stress fibers. The rho GDI action was prevented by comicr...

Induction of p21 in senescent human fibroblasts plays a key role in the inactivation of cyclin-dependent kinases and the resulting irreversible growth arrest in the early stages of cell senescence. We found that RNA-binding proteins are critical regulators of p21 during senescence. Two RNA-binding proteins, CUGBP1 and calreticulin (CRT), interact with the same nucleotide sequences within the 5'...

In many cell types, p53-mediated growth inhibition is dependent on induction of p21, which is an inhibitor of cyclin-dependent kinases that are required for cell cycle progression. Failure of mutant p53 proteins to transactivate p21 may lead to uncontrolled proliferation. Because many ovarian cancers have mutations in the p53 gene, we examined p21 levels in normal and malignant ovarian epitheli...

The 21,000-dalton protein (p21) encoded by the ras oncogene of Harvey murine sarcoma virus (v-Ha-ras) becomes phosphorylated (pp21) in vivo and in vitro on threonine residue 59. p21 molecules encoded by cellular ras genes (c-Ha-ras-1) contain an alanine at position 59, and thus these p21 molecules are not phosphorylated. In this investigation, recombinant ras genes have been constructed between...

Background—The p21 gene mediates growth arrest by inhibiting G1 cyclin dependent kinases and has been considered as a downstream eVector of the tumour suppressor gene p53. Aim—To analyse the role of p21 in gestational trophoblastic disease. Methods—The immunohistochemical expression of p21 gene was measured in 33 placentas, 28 partial hydatidiform moles, 54 complete hydatidiform moles, and 13 c...

AIM The objective of this study was to evaluate the prognostic value of p21 alone and in combination with p53 or p27 for different histological subtypes of epithelial ovarian cancer and disease-free survival. PATIENTS AND METHODS The specimens were obtained at primary surgery from a series of 129 ovarian carcinomas in FIGO stages I-II. The technique of tissue microarray and immunohistochemist...

Following DNA damage caused by exogenous sources, such as ionizing radiation, the tumour suppressor p53 mediates cell cycle arrest via expression of the CDK inhibitor, p21. However, the role of p21 in maintaining genomic stability in the absence of exogenous DNA-damaging agents is unclear. Here, using live single-cell measurements of p21 protein in proliferating cultures, we show that naturally...