CXCR4 and neoplasm: Their collaborative role in angiogenesis parallels a similarjoint action in noncancer processes involving neovascularisation (e.g., [141]), and it has been suggested inthe context of tumor angiogenesis that their actions may be synergistic [34].It is not surprising that these two entities are closely linked; VEGF receptorsand CXCR4 have common regulatory pathways.