ABCC4 and prostate cancer: Moreover, supplementation of pge2 to the co-culture system of CD8+ T cells and RM1 cells (WT or ABCC4 KO) eliminated the boosting effects of ABCC4 depletion in tumor cells on CD8+ T cells (Figure 4C and 4D), strongly supporting the speculation that the effects of ABCC4 on anti-tumor immunity depended on its regulation of pge2 release from prostate cancer cells.