該基因編碼的蛋白質屬于高度保守的細胞周期蛋白家族，其成員在細胞周期內具有顯著的蛋白質豐度周期性。細胞周期蛋白起著調節CDK激酶的作用。不同的細胞周期蛋白表現出不同的表達和降解模式，這有助于每個有絲分裂事件的時間協調。該細胞周期蛋白與CDK2形成復合物并作為其調節亞單位發揮作用，其活性是細胞周期G1/S轉換所必需的。這種蛋白在G1-S相邊界處積累，并隨著細胞進入S相而降解。這種基因在許多腫瘤中過度表達，導致染色體不穩定，從而可能有助于腫瘤的發生。研究發現，這種蛋白與NPAT蛋白的磷酸化（與ATM位點對應的核蛋白）有關并參與其中，NPAT蛋白參與細胞周期調節組蛋白基因的表達，并在無prb的情況下在促進細胞周期進展中起到關鍵作用。
The protein encoded by this gene belongs to the highly conserved cyclin family, whose members are characterized by a dramatic periodicity in protein abundance through the cell cycle. Cyclins function as regulators of CDK kinases. Different cyclins exhibit distinct expression and degradation patterns which contribute to the temporal coordination of each mitotic event. This cyclin forms a complex with and functions as a regulatory subunit of CDK2, whose activity is required for cell cycle G1/S transition. This protein accumulates at the G1-S phase boundary and is degraded as cells progress through S phase. Overexpression of this gene has been observed in many tumors, which results in chromosome instability, and thus may contribute to tumorigenesis. This protein was found to associate with, and be involved in, the phosphorylation of NPAT protein (nuclear protein mapped to the ATM locus), which participates in cell-cycle regulated histone gene expression and plays a critical role in promoting cell-cycle progression in the absence of pRB.