COL1A1 and breast cancer: To further provide evidence that MERTK in osteoblasts represents a novel target to increase bone volume in bone-seeking tumors, we used the syngeneic EO771 breast cancer bone metastasis model and injected luciferase transduced EO771 cells into Mertkflox/flox and Col1a1-cre+;Mertkflox/flox C57BL/6J mice.