MAPK3 and breast neoplasm: E0771 breast tumors developed aggressively in SRC-3f/f:Foxp3Cre-ERT2/+ female mice treated with vehicle, but tumors failed to progress beyond a short initial period of growth in SRC-3f/f:Foxp3Cre-ERT2/+ female mice treated with tamoxifen (SI Appendix, Fig. S8 B and C).