ERBB2 and neoplasm: Interestingly, previous studies showed that the MMTVneu model is particularly susceptible to additional mutations in DDR regulators, as is the case in bi-transgenic mice expressing the HER2 oncogene and an inactivated form of p53 (WAP-p53-172H) with a tumor latency shortened to 154 days (compared to 205 days of the MMTVneu) [47].