The number of deleterious mutation-affected oncogenes and tumor suppressor genes per tumor is shown in Fig. 3C. These results indicate that the breast cancer cells developed from Tp53 and Pten deficient mouse MGECs contain many other mutated genes and the accumulation of these gene mutations may play an essential role in breast cancer initiation and progression induced by P53 and Pten deficiencies. This evidence concerns the gene PTEN and breast cancer.