SIRT1 and colorectal cancer: Additionally, the ubiquitin-conjugating E2 enzyme variant protein 1 (Ube2v1), an E2 member of the ubiquitin-proteasome system, promotes Ubc13-mediated ubiquitination and degradation of SIRT1, thereby inhibiting H4K16 acetylation and the transcription of autophagy-related genes in colorectal cancer (76).