Binds and inhibits CYCD2-1/CDKA-1 complex kinase activity. May target specifically CDKA-1. Specifically interacts with CDKA-1, but not with CDKB1-1. Distributed in a ponctuate pattern. A number of isoforms are produced. According to EST sequences. Highly expressed in actively dividing cells of root pericycle and suspension cell culture. Expressed in the G1/S phases and reaches a peak at the G2 phase. By auxin in roots. Treatment with auxin induces lateral root initiation. Belongs to the CDI family. ICK/KRP subfamily.