We found that down regulation of CXCR7 decreased the level of activation of phospho-EGFR and phosho-ERK1/2, which suggests a strong association of CXCR7 with EGFR in breast cancer in accordance with our in situ co-IP data and confirms a role of CXCR7 in EGFR mediated ERK signaling. Here, MAPK3 is linked to breast cancer.