As tumor penetrance and lifespan in P0-GGFβ3;Trp53+/−;Erbb4flox/flox mice and P0-GGFβ3; Trp53+/−; mice was similar, we concluded that the floxed Erbb4 alleles did not impede tumorigenesis or worsen the survival of these mice. The gene discussed is ERBB4; the disease is neoplasm.