Similar studies were performed using the PyMT model of breast cancer with modulations in HGFL or RON tyrosine kinase (TK) expression [17], with PyMT TK−/− and PyMT Hgfl−/− tumors having less Lin−CD29HiCD24+ BCSCs and reduced self-renewal compared to controls (Figure 1D and 1E). This evidence concerns the gene MST1R and breast cancer.