SKI and hepatocellular carcinoma: By contrast, the SnoN protein is stabilized by signals that promote actin polymerization in hepatocytes.171–173 Interestingly, Ski and SnoN regulation mediated by actin polymerization dynamics is lost in hepatoma cells, affecting notably the TGF-β signaling outcome.172 Other studies have shown that cAMP also increases the Ski protein levels, but in rat Schwann cells.168 Therefore, it is clear that cell density, polarity, and actin-cytoskeleton dynamics regulate Ski and SnoN protein stability, as well as their subcellular localization (Fig. 2).