BRCA1 and neoplasm: As occurs in a traditional GEMM with Brca1;Trp53;Rb1;Nf1 genotype (23), some tumors generated by tumor suppressor gene inactivation without MYC overexpression showed gain or amplification of the Myc locus on mouse chromosome 15 (SI Appendix, Fig. S1E) together with MYC protein expression (SI Appendix, Fig. S1F).