MST1R and breast cancer: Further, when cultured along with R7 tumor epithelial cells (derived from a mammary tumor from MMTV-Ron mice), splenic-derived T-cells from MMTV-RonHGFL−/− mice had increased cytotoxic activity compared to cells from MMTV-RonHGFL+/+ mice as judged by a reduction in overall mammary tumor cell number (Figure 6E).