SUMO in cancer--wrestlers wanted.

SUMO (small ubiquitin-related modifier) represents a class of ubiquitin-like proteins that is conjugated, like ubiquitin, by a set of enzymes to cellular regulatory proteins, including oncogenes and tumor suppressor genes, that play key roles in the control of cell growth, differentiation and apoptosis. SUMO conjugation affects substrates' subcellular localization and stability as well as transcriptional activities. Given the substrates involved, protein SUMOylation would be expected to be important in the course of tumorigenesis and, accordingly, altered in human cancer. Although evidence to support this notion is still scarce, this review summarizes the current knowledge of protein sumoylation and highlights the challenges to be addressed in the context of human cancer.