Exceptionally large tumors accounted for a much smaller percentage of the total tumor burden in Braf;Cas9 mice than in any other mouse genotype: only 0.9% of neoplastic cells in Braf;Cas9 mice were from tumors with >300,000 cells compared with 13.1% and 25.4% for G12D;Cas9 and Egfr;Cas9 mice, respectively. This evidence concerns the gene EGFR and neoplasm.