CXCL12 and neoplasm: Infiltrated immune cells shift their phenotypes from anti-tumor, also known as pro-inflammatory phenotypes, to pro-tumor phenotypes because tumor cells increase interleukins and chemokines such as IL-2, IL-4, IL-6, IL-7, IL-10, IL-12, and CXCL12 concentrations (Fig. 2) [27–29].