CDKN1B
小结
CDKN1B编码蛋白 (cyclin-dependent kinase (CDK) inhibitor 1B)，也称为p27或KIP1，是Cip/Kip蛋白家族的成员，并有助于控制细胞周期进程、增殖、运动和凋亡。p27蛋白广泛表达，并同时位于细胞核和细胞质。核p27通过控制细胞周期的G1期到S期而起到肿瘤抑制剂的作用。相反，细胞质p27可以刺激细胞迁移而具有促致癌作用。p27的胚系突变可导致多发性内分泌肿瘤（MEN）综合征。由于蛋白降解的增加，低p27水平在几种不同类型的上皮性肿瘤中普遍存在，如上消化道癌、皮肤、造血系统恶性肿瘤、胶质瘤和肉瘤，并且通常与侵袭性肿瘤生长和较差的临床结果相关。
CDKN1B (cyclin-dependent kinase (CDK) inhibitor 1B), also called p27 or KIP1, is a member of the Cip/Kip protein family and helps control cell cycle progression, proliferation, motility, and apoptosis. The p27 protein is ubiquitously expressed and located both in the nucleus and in the cytoplasm. Nuclear p27 functions as a tumor suppressor by controlling cell cycle progression from G1 to S phase, specifically by inhibiting the binding of cyclins A and E to CDK2. Conversely, cytoplasmic p27 may have a pro-oncogenic role by stimulating cell migration through mechanisms largely independent of its CDK-inhibiting function. The activity of p27 is largely regulated by protein degradation, and proteolysis is triggered by its CDK-dependent phosphorylation and subsequent ubiquitination by SCF complexes. Germline mutations in p27 can cause a multiple endocrine neoplasia (MEN) syndrome. Low p27 levels due to increased protein degradation are prevalent in several different types of epithelial tumors, such as cancers of the upper gastrointestinal tract, skin, hematopoietic malignancies, gliomas, and sarcomas, and are commonly correlated with aggressive tumor growth and poor clinical outcome.