These results suggest that, in normal mammary tissue, the LCn-3 PUFA, through their ability to maintain the ERK1/2 and PI3K/Akt/mTOR at low level of activities, could have the potential to exert a preventive action against the risk of breast cancer, comparable to that of selective estrogen receptor modulators, now approved for breast cancer prevention (Tamoxifen and Raloxifene). The gene discussed is MAPK3; the disease is breast cancer.