Elevated macrophage numbers in the endometrium of women with endometriosis may be due to the increased levels of macrophage migration inhibitory factor (MIF) and monocyte/macrophage activating chemoattractant protein (MCP-1/CCL2) that simultaneously limit macrophage migration from and recruitment of macrophages into the endometrium, respectively (73, 74). This evidence concerns the gene MIF and endometriosis.