CXCL12 and neoplasm: When examining the factors that could contribute to CD8+ Teff tumor recruitment, we found that CD8+ Teffs expressed the chemokine receptors CXCR3 and CXCR4, while the TME produced abundant CXCL9 and CXCL12, which are the key chemokines known to bind CXCR3 and CXCR4, respectively.