Indeed, we have previously demonstrated that CXCL12 either induces HB-EGF shedding in monocytes, which in turn phosphorylates HER1 in bystander cancer cells [19], and transinhibits HER1 via intracellular G protein-dependent signaling in CXCR4/HER1 double-positive cells [21]. Here, CXCL12 is linked to cancer.