CCL2 and breast cancer: Overexpression of CCR2 in SUM225 (CCR2-H) breast cancer cells increased their invasiveness, correlating with increased MET expression and activity.27,33 To determine whether the increased cellular responsiveness of CCL2 and HGF co-treatment were due to levels of CCR2 and MET expression, we compared the activity between pHAGE control cells and SUM225 CCR2-H cells, with or without CCL2 and HGF treatment.