By contrast, in the FVB/N MMTV-Neu (Neu+) model, which represents the HER2-amplified subtype of human breast cancer (8), animals had late mammary tumor occurrence (∼20 weeks after birth) and slower tumor growth rate, which was accompanied with mild reduction of grip strength, rotarod performance, and muscle contraction force (9). This evidence concerns the gene ERBB2 and breast cancer.