By crossing heterozygous animals of both genotypes, it was observed that Eμ-c-myc;Eμ-pim1 mice expressing high levels of c-myc were not viable, whereas Eμ-c-myc;Eμ-pim1 mice expressing low levels of c-myc were viable and showed a low tumor incidence. This evidence concerns the gene MYC and neoplasm.