该基因编码的蛋白质属于高度保守的细胞周期蛋白家族，其成员在细胞周期内具有显著的蛋白质丰度周期性。细胞周期蛋白起着调节CDK激酶的作用。不同的细胞周期蛋白表现出不同的表达和降解模式，这有助于每个有丝分裂事件的时间协调。该细胞周期蛋白与CDK4或CDK6形成复合物并作为其调节亚单位发挥作用，其活性是细胞周期G1/S转换所必需的。这种蛋白与肿瘤抑制蛋白Rb的磷酸化相互作用并参与其中。据报道，与该细胞周期蛋白相关的CDK4活性对紫外线照射后细胞周期通过G2期进入有丝分裂是必要的。一些转录变体编码不同的亚型已被发现的这个基因。
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 CDK4 or CDK6, whose activtiy is required for cell cycle G1/S transition. This protein has been shown to interact with and be involved in the phosphorylation of tumor suppressor protein Rb. The CDK4 activity associated with this cyclin was reported to be necessary for cell cycle progression through G2 phase into mitosis after UV radiation. Several transcript variants encoding different isoforms have been found for this gene.