Statistical analysis demonstrated that the rate of MMTV-ErbB2 induced mammary tumor onset was delayed in mice in which the Pparγ1 gene had been deleted through Cre recombinase (by the log-rank test, p = 0.043; by Wilcoxon rank-sum test, p = 0.028 or by the Tarone-Ware test, p = 0.033) (Table S1). This evidence concerns the gene PPARG and breast cancer.