[5] 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.

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 activity is required for cell cycle G1/S transition.

The CDK4 activity associated with this cyclin was reported to be necessary for cell cycle progression through G2 phase into mitosis after UV radiation.

[6] Mutations in CCND3 are implicated in cases of breast cancer.