In the context of cholangiocarcinoma, it has been demonstrated that p27kip1 undergoes SUMOylation, a process mediated by upstream molecules such as ubiquitin-conjugating enzyme E2 I (UBE2I)64 and RING finger protein (RNF4),68 influencing the tumorigenic processes. The gene discussed is UBE2I; the disease is cholangiocarcinoma.