Importantly, the model used here showed some similarity to the behavior of the disease in the human population, such as the development of less aggressive tumors in older mice, the fact that human and mouse ERBB2 tumors partially share gene expression signatures and that, at the protein level, mouse and human mammary tumors that did not disseminate along their progression show high levels of pAKT1(S473). The gene discussed is ERBB2; the disease is breast cancer.