In order to test if dystrophin, dysferlin and calpain-3 have tumor-suppressor effects in vivo, we generated double-mutant mouse lines, i.e. dystrophin-deficient (mdx) mice with additional lack of either dysferlin (Dmd −/− Dysf −/−) or calpain-3 (Dmd −/− Capn3 −/−). The gene discussed is CAPN3; the disease is neoplasm.