Speedy protein A (Spdya)

Regulates the G1/S phase transition of the cell cycle by binding and activating CDK1 and CDK2 (PubMed:15611625). Contributes to CDK2 activation without promoting CDK2 phosphorylation, by inducing a conformation change of the CDK2 T- loop which obstructs the substrate-binding cleft before kinase activation.

Interferes with CDKN1B-mediated inhibition of CDK2. Mediates cell survival during the DNA damage process through activation of CDK2 (By similarity).