Similar to the ERK activation seen in HCC cells in vitro, we found that sorafenib increased ERK activation in orthotopic Hep3B xenografts and in two murine models of spontaneous HCC (in Mst1−/−Mst2F/− mice and chemically-induced carcinogenesis) (Fig. 1c–e)22, 23. The gene discussed is MST1; the disease is hepatocellular carcinoma.