BACKGROUND The protein p27 (p27(Kip1)) is a member of the cyclin-dependent kinase inhibitor family, which negatively regulates cell cycle progression, and the phosphorylation of p27 has been proven to affect its stability and nuclear export. Clinical studies on the relation between p27 and phosphorylated p27 (p-p27Ser10) in breast invasive ductal carcinomas are still scarce. METHODS We examin...

Background—Rapamycin is a potent inhibitor of smooth muscle cell (SMC) proliferation and migration. Rapamycinmediated inhibition of SMC proliferation is associated with upregulation of the cyclin-dependent kinase inhibitor p27. Previously, we showed that mixed embryonic fibroblasts obtained from p27(2/2) mice were relatively rapamycin-resistant, suggesting that p27 plays an integral role in mod...

Nonpathogenic simian immunodeficiency virus SIVagm infection of African green monkeys (AGMs) is characterized by the absence of a robust antibody response against Gag p27. To determine if this is accompanied by a selective loss of T-cell responses to Gag p27, we studied CD4(+) and CD8(+) T-cell responses against Gag p27 and other SIVagm antigens in the peripheral blood and lymph nodes of acutel...

In mammalian cells, the heterodimeric kinase cyclin E/CDK2 (EK2) mediates cell cycle progress from G1 phase into S phase. The protein p27Kip1 (p27) binds to and inhibits EK2; but EK2 can phosphorylate p27, and that leads to the deactivation of p27, presumably liberating more EK2 and forming a positive-feedback loop. It has been proposed that this positive-feedback loop gives rise to binary (all...

p27 is a cyclin-dependent kinase inhibitor that regulates the progression of cells from G(1) to S phase of the cell cycle. Loss of p27 has been associated with disease progression and with an unfavourable outcome in prostate cancer. In this study, we investigated whether exogenous p27 expression in the human androgen-independent prostate cancer PC3 cell line had any effect on cell growth, and w...

p27Kip1 (p27) is a negative regulator of proliferation and a tumor suppressor via the inhibition of cyclin-CDK activity in the nucleus. p27 is also involved in the regulation of other cellular processes, including transcription by acting as a transcriptional co-repressor. Loss of p27 expression is frequently observed in pancreatic adenocarcinomas in human and is associated with decreased patien...

The cell cycle is regulated by a number of inhibitors, including p27Kip1 (p27), which belongs to the kip1 family. By binding to the cyclin/cyclin-dependent kinase complexes, it regulates progression of G1 to S phase in the cell cycle. It has been reported that p27 knockout mice develop multiorgan hyperplasia and intermediate lobe pituitary tumors secreting ACTH. Previously, we and others have b...

In the present study, we conducted a comprehensive analysis on the clinical roles of p27 protein and p27 gene in digestive tract cancers (DTCs). First, we performed immunohistochemistry staining and found that p27 protein was down-regulated in DTCs. Then we collected 62 publications and calculated the combined hazard ratios (HRs), odds ratios (ORs) and 95% confidence intervals (95% CIs) to clar...

Opacification of the posterior capsule depends on replication of the residual lens epithelial cells lining the capsule. However, the mechanisms in the regulation of lens cell proliferation have not been determined. The purpose of this study is to examine the expression of p27(KIP1), a cyclin-dependent kinase inhibitor, and its phosphorylation, and cyclin D1 in lens epithelial cells after extrac...

The levels of proteins that control the cell cycle are regulated by ubiquitin-mediated degradation via the ubiquitin-proteasome system (UPS) by substrate-specific E3 ubiquitin ligases. The cyclin-dependent kinase inhibitor, p27kip1 (p27), that blocks the cell cycle in G1, is ubiquitylated by the E3 ligase SCF-Skp2/Cks1 for degradation by the UPS. In turn, Skp2 and Cks1 are ubiquitylated by the ...