We immunohistochemically examined specimens of 215 surgically resected non-small cell lung cancers (NSCLCs) for p27KIP1 protein (p27) expression and the growth fraction determined by the Ki-67 labeling index (LI). The NSCLCs analyzed showed considerable heterogeneity in both p27 and Ki-67 LIs; 25 of 207 (13%) lacked p27 expression (p27 LI < 5%), and 116 of 215 (54%) showed a high Ki-67 LI (>30%...

p27 is a critical CDK inhibitor involved in cell cycle regulation, and its stability is critical for cell proliferation. Constitutive photomorphogenic 1 (COP1) is a RING-containing E3 ubiquitin ligase involved in regulating important target proteins for cell growth, but its biological activity in cell cycle progression is not well characterized. Here, we report that p27Kip1 levels are accumulat...

The major internal structural polypeptide (p27) of Rous sarcoma virus (RSV), and the analogous polypeptide (P27(0)) OF Rous-associated virus-O (RAV-O), an endogenous virus released spontaneously by some chicken cells) have been cleaved selectively at a single aspartylprolyl peptide bond to yield two fragments. The NH2- and COOH-terminal amino acid sequences of p27 and p27(0) and their mild acid...

In eukaryotic cells, the coordinated activation of different cyclin-dependent kinases regulates entry into S-phase. In vitro and in nonproliferating cells, p27 associates with and inhibits cyclin/cycin-dependent kinase (CDK) holoenzymes containing either CDK4, CDK6, or CDK2. Although many different types of proliferating cells contain p27 protein, neither the interactions of p27 with cyclin/CDK...

Cyclin-dependent kinase inhibitor p27, a critical determinant for cell cycle progression, is an important regulation target of mitogenic signals during arterial injury. In this study, we show in rat aortic smooth muscle cells that PDGF-BB down-regulated p27 protein and mRNA in an ERK-dependent mechanism. Inhibition of ERK, but not other subtypes of the mitogen-activated protein kinase family, p...

BACKGROUND: Pelvic floor disorders affect almost 50% of aging women. An important role in the pelvic floor support belongs to the levator ani muscle. The p27/kip1 (p27) protein, multifunctional cyclin-dependent kinase inhibitor, shows changing expression in differentiating skeletal muscle cells during development, and relatively high levels of p27 RNA were detected in the normal human skeletal ...

PURPOSE p27(Kip1)(p27) is a universal cyclin-dependent kinase inhibitor that inhibits cell cycle transition from G(1) to S phase and is primarily regulated at the post-transcriptional level via the ubiquitin-proteasome pathway. In vitro data suggest that p27 degradation may be accelerated by the c-Jun activation domain binding protein-1 (JAB1), originally identified as a coactivator of the gene...

Purpose: The purpose is to evaluate expression levels of Jun activation domain-binding protein 1 (JAB1) in breast cancer tissue and adjacent normal tissue, to determine whether JAB1 expression is associated with p27 expression in invasive breast carcinomas, and to evaluate the prognostic significance of JAB1 and p27 in node-negative breast cancer. Experimental Design: JAB1 levels were measured ...

Loss of the cyclin-dependent kinase inhibitor p27(Kip1) leads to an overall increase in animal growth, pituitary tumors, and hyperplasia of hematopoietic organs, yet it is unknown whether all cells function autonomously in response to p27(Kip1) activity or whether certain cells take cues from their neighbors. In addition, there is currently no genetic evidence that tumor suppression by p27(Kip1...

p27Kip1 is a member of the Cip1/Kip1 family of cyclin-dependent kinase inhibitors and is a potential tumor suppressor gene. Low levels of p27 are associated with poor prognosis in a variety of tumors, including breast, colon, prostate, and lung carcinomas. In the present study, p27 protein expression was investigated by immunohistochemistry and Western blot analysis in a series of 82 epithelial...