At the same time, 1/6 of the mice implanted with metastatic tumors had p53, PTEN, and RB1 mutations, and 1/2 had p53, PTEN, RB1, and NF1 mutations, and these tumors respond to both chemotherapy and endocrine therapy, improving understanding and awareness of specific molecular subtypes of breast cancer (88). This evidence concerns the gene RB1 and breast carcinoma.