CXCR4 and neoplasm: The mitogenic activity mediated by CXCL12-CXCR4 was also reported in meningioma, in which CXCR4 activation increased DNA synthesis through activation of ERK1/2 in primary cultures and its expression level significantly correlated with Ki-67 proliferation index of the original tumor tissue [150, 151], while CXCR7 was mainly localized in tumor endothelia [152].