CCL2 and neoplasm: A further contribution of CAFs during tumorigenesis is the promotion of the immunologic tolerization of the tumor as a result of imbalances in the tumor microenvironment, including alterations in antigen-presenting-cell subsets, co-stimulatory and co-inhibitory molecule alterations such as CXCR4, IL2 or CCL2 and altered ratios of effector T cells and regulatory T cells [15].