ESR1 and breast cancer: Yet, basal-like breast cancers and cell lines exhibit higher levels of CCR2 expression, compared to luminal breast cancer cells.26 As SUM225 cells express hormone receptors and HER2, other oncogenic pathways, notably ER, HER2, and EGFR may be more important in modulating cell growth than CCL2 or HGF.51,57 Interestingly, CCR2 overexpression increased cooperative responses between CCL2 and HGF in enhancing cell survival and invasion compared to control cells.