The CDK2-associated cyclin A1 is essential for spermatogenesis, and contributes to leukemogenesis, but its detailed molecular functions are unclear. Several novel cyclin A1/CDK2 interaction partners have been identified by means of a yeast triple-hybrid approach, including INCA1, KARCA1 and PROCA1. These proteins link the cyclin A1-CDK2 complex to diverse cellular processes, such as DNA repair, signalling and splicing [].One of the new genes has been cloned and characterised, and named INCA1 (inhibitor of CDK interacting with cyclin A1). The nuclear INCA1 protein is evolutionarily conserved but shares no similarity with any known gene. This novel protein and two other interacting partners serve as substrates for the cyclin A1-CDK2 kinase complex [].
