Tumors induced by the Eμ-Myc, K-Ras and HER2 transgenes were greatly accelerated in both Dmp1+/− and Dmp1−/− backgrounds with no differences between groups lacking one or two Dmp1 alleles, suggesting haploid-insufficiency of Dmp1 in tumor suppression in these mouse models of human cancers [11], [26], [30]. This evidence concerns the gene ERBB2 and cancer.