GUK1 and cancer: The function of TRPC4AP (transient receptor potential cation channel subfamily C member 4–associated protein) has been shown to be involved in the ubiquitination of E3 ligase skp222 and the activation of c-Jun NH(2) terminal kinase and transcription factor AP-1.23 Guanylate kinase 1 (GUK1) is an enzyme that catalyzes the transfer of a phosphate group from ATP to guanosine monophosphate (GMP) to form guanosine diphosphate (GDP) and is believed to be a good target for cancer chemotherapy.24 Its expression on tumor-specific T cells was not previously reported.