CXCL12 and cancer: The immunosuppressive and tumorigenic characteristics of microglia were further augmented by the secretion of growth factors such as NGF which can counter inflammatory responses (114), MYDGF which increases viability of cancer cells (115), FGF1 which supports angiogenesis and tumor growth and invasion, and of cytokines CCL22 and CXCL12 which attract pro-tumor immunosuppressive cells (7).