Mice injected with NRASG12V-Ova developed HCC and occasionally combined HCC-CCA as demonstrated by cytokeratin 7 (CK7)-positive ductal areas (Fig. 1C, D), whereas intrahepatic delivery of KRASG12V-Ova resulted in the formation of predominantly CK7+ CCA (Fig. 1E, F). The gene discussed is KRT7; the disease is hepatocellular carcinoma.