P27蛋白是重要的细胞周期蛋白依赖性激酶抑制因子之一,它可通过抑制多种细胞周期依赖性蛋白激酶的活性对细胞周期进行调控。P27蛋白表达水平与肿瘤的发生、发展及预后密切关联,许多恶性肿瘤的P27蛋白表达量都有不同程度的降低。现主要介绍恶性肿瘤中P27蛋白表达降低的主要调控机制,即蛋白的降解和胞核蛋白的胞浆转移。 P27 protein is one of the important inhibitors of cyclin-dependent kinase. It can regulate the cell cycle by inhibiting the activity of many cell cycle-dependent protein kinases. The expression of P27 protein is closely related to the occurrence, development and prognosis of tumor, and the expression of P27 in many malignant tumors is reduced to some extent. We mainly introduce the main regulatory mechanisms of P27 protein expression in malignant tumors, namely the degradation of protein and the cytoplasm transfer of nuclear protein.