CGI-121 has been shown to bind to the p53-related protein kinase (PRPK). PRPK is a novel protein kinase which binds to and induces phosphorylation of the tumor suppressor protein p53. CGI-121 is part of a conserved protein complex, KEOPS. The KEOPS complex is involved in telomere uncapping and telomere elongation. Interestingly this family also include archaeal homologs, formerly in the DUF509 family. A structure for these proteins has been solved by structural genomics.