HRAS and breast carcinoma: We previously reported that a single oral dose of DMBA administered to heterozygous BALB/c Trp53 knockout female mice significantly accelerated induction of ERα-positive mammary carcinomas with frequent Hras mutations at codon 61 (10/10 mice) as compared with BALB/c wild type mice, suggesting the combination of Trp53 gene function deficiency and exogenous factors contributed the increased susceptibility to mammary carcinogenesis (Machida and Imai, 2021).