Binds and inhibits CYCD2-1/CDKA-1 complex kinase activity. Regulates cell division which is crucial for plant growth, development and morphogenesis. May regulate early lateral root initiation by blocking the G1/S phase transition. Controls the mitosis-to-endocycle transition and the onset of the endoreduplication cycle during leaf development through inhibition of mitotic CDKA-1 kinase complexes. Specifically targets CDKA-1. Specifically interacts with CDKA-1, but not with CDKB1-1. Homogeneously distributed. Highly expressed in root pericycle and cell suspension culture during cell cycle arrest. Expressed early in the G1 phase and then disappears. More abundant in endoreduplicating than in mitotically dividing tissues (at protein level). Down-regulated by auxin in roots. Phosphorylated. Treatment with auxin induces lateral root initiation. ICK2/KRP2 protein abundance is regulated post-transcriptionally through CDK phosphorylation and proteasomal degradation. Belongs to the CDI family. ICK/KRP subfamily.