PTGS2 and cancer: Given the known pleiotropic suppressive effects of the COX2/PGE2 axis on tumor-specific CTLs immunity, and the documented ability of blockade of tumor-associated COX2 to skew toward a type-1 cytokine response [25, 26], we anticipated a negative correlation between COX2 and the local development CTL cells associated with the cancer microenvironment.