KRAS and hepatocellular carcinoma: While mice deficient for the caspase-2 gene (Casp2−/−) do not develop spontaneous age-related tumors19, they show enhanced genomic instability and increased tumorigenesis in different mouse models, including EμMyc lymphomas7,20, Atm−/−thymomas8; MMTV/c-neu mammary tumors11, K-Ras-induced lung tumors10, and DEN-induced hepatocellular carcinoma (HCC)21.