这个基因编码一种有效的细胞周期蛋白依赖激酶抑制剂。编码蛋白结合并抑制细胞周期蛋白依赖性激酶2或-细胞周期蛋白依赖性激酶4复合物的活性，因此在G1期起调节细胞周期进展的作用。该基因的表达受到肿瘤抑制蛋白p53的严格控制，通过该蛋白介导p53依赖细胞周期G1期停滞，以响应各种应激刺激。该蛋白可与DNA聚合酶辅助因子增殖细胞核抗原相互作用，在S期DNA复制和DNA损伤修复中起调节作用。据报道，这种蛋白被casp3样caspases特异性地切割，从而导致细胞周期蛋白依赖性激酶2的显著激活，并可能在caspase激活后的凋亡执行中起到作用。缺乏这种基因的小鼠有能力再生受损或缺失的组织。已发现该基因的多个选择性剪接变体。
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.