Although epigenetic inactivation of Rassf1A and of Rassf5b/Nore1b has been reported in HCC (Calvisi et al, 2006; Macheiner et al, 2006), whether hepatocyte Mst1/2 activation involves Rassf(1-6) polypeptides, or as yet unidentified mechanisms is not known. The gene discussed is MST1; the disease is hepatocellular carcinoma.