Cyclin-dependent protein kinase regulatory subunit and adaptor%3B interacts with Cdc28p (aka Cdk1p)%3B required for G1/S and G2/M phase transitions and budding%3B mediates phosphorylation and degradation of Sic1p%3B modulates proteolysis of M-phase targets through interactions with the proteasome%3B role in transcriptional regulation%2C recruiting proteasomal subunits to target gene promoters%3B human homologs CKS1B and CKS2 can each complement yeast cks1 null mutant