Xe-p9, or CDC28 protein kinase regulatory subunit 2, is a human gene encoded by CKS2. It may also be known as: Cyclin-dependent kinases regulatory subunit 2; CKS-2; CKSHS2. The encoded protein has an amino acid length of 79 and a mass of 9.9 kDa. Xe-p9 is a member of the CKS family. Homologs of this gene exist in other organisms, including: Arabidopsis.