PTGER4 and neoplasm: Next, we knocked down the Ptger2 and Ptger4 in CD8+ T cells (encoding EP2/4 receiving pge2 signaling) and found supplementation of pge2 no longer inhibited CD8+ T cell function (Figure 4E), underlying the determining roles of ABCC4-PGE2-EP2/EP4 axis in regulating anti-tumor functions of CD8+ T cells in prostate cancer.