Probable cyclin-dependent protein kinase (CDK) inhibitor that functions as a repressor of mitosis in the endoreduplication cell cycle (PubMed:26546445). Acts as a potent cell cycle inhibitor, regulating a hydroxyurea-dependent checkpoint in leaves (PubMed:24399300). Expressed in root meristems after induction. Up-regulated by DNA damage and oxidative stress (PubMed:24399300). Down-regulated by iron excess treatment (PubMed:25624148). Extended C-terminus.