The protein encoded by the gene CCNA2, Cyclin A2, belongs to the highly conserved cyclin family. Members of the cyclin family 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. In contrast to cyclin A1, which is present only in germ cells, Cyclin A2 is expressed in all tissues tested. Cyclin A2 binds and activates CDC2 or CDK2 kinases, and thus promotes both cell cycle G1/S and G2/M transitions [taken from NCBI Entrez Gene ID: 890].