CD8A and colorectal carcinoma: However, CXCR6 expression can obviously be induced on the surface of colon tumor-infiltrating CD8+ T cells by yet-to-be-defined mediators of the local microenvironment, and CXCR6+ CD8+ T cells in primary human CRC lesions could recently be characterized by the marked expression of cytotoxic effector markers, indicating their potent antitumor effector function [25].