SIRT2 and neoplasm: Subsequent litters were screened to identify two groups, each of control and experimental mice: (1) Sirt2+/+ or Sirt2−/− mice hemizygous for both transgenes (hereafter, Sirt2+/+ HCC or Sirt2−/− HCC); and (2) Sirt2+/+ or Sirt2−/− mice negative for the tet-MYC transgene (Sirt2+/+ or Sirt2−/− with a normal liver phenotype), serving as tumor-free controls.