CXCL12 and cancer: CXCL12 inhibits T cell trafficking into tumors by binding the T cell surface receptor CXCR4 and pharmacologic inhibition of CXCR4 with AMD3100 (plerixafor), a drug used for mobilization of hematopoietic stem cells from bone marrow, led to increased T cell infiltration into tumors and synergistically decreased cancer cell numbers when combined with anti-PD-L1 therapy (30).