這個基因編碼一種有效的細胞周期蛋白依賴激酶抑制劑。編碼蛋白結合并抑制細胞周期蛋白依賴性激酶2或-細胞周期蛋白依賴性激酶4復合物的活性，因此在G1期起調節細胞周期進展的作用。該基因的表達受到腫瘤抑制蛋白p53的嚴格控制，通過該蛋白介導p53依賴細胞周期G1期停滯，以響應各種應激刺激。該蛋白可與DNA聚合酶輔助因子增殖細胞核抗原相互作用，在S期DNA復制和DNA損傷修復中起調節作用。據報道，這種蛋白被casp3樣caspases特異性地切割，從而導致細胞周期蛋白依賴性激酶2的顯著激活，并可能在caspase激活后的凋亡執行中起到作用。缺乏這種基因的小鼠有能力再生受損或缺失的組織。已發現該基因的多個選擇性剪接變體。
This gene encodes a potent cyclin-dependent kinase inhibitor. The encoded protein binds to and inhibits the activity of cyclin-cyclin-dependent kinase2 or -cyclin-dependent kinase4 complexes, and thus functions as a regulator of cell cycle progression at G1. The expression of this gene is tightly controlled by the tumor suppressor protein p53, through which this protein mediates the p53-dependent cell cycle G1 phase arrest in response to a variety of stress stimuli. This protein can interact with proliferating cell nuclear antigen, a DNA polymerase accessory factor, and plays a regulatory role in S phase DNA replication and DNA damage repair. This protein was reported to be specifically cleaved by CASP3-like caspases, which thus leads to a dramatic activation of cyclin-dependent kinase2, and may be instrumental in the execution of apoptosis following caspase activation. Mice that lack this gene have the ability to regenerate damaged or missing tissue. Multiple alternatively spliced variants have been found for this gene.