CD4 and neoplasm: Exposure of MSCs to PGE2 polarizes M1 macrophages to the M2 phenotype.MSCs drive CD8+ T-cells to an immunosuppressive phenotype and inhibit pro-inflammatory cytokine secretion from Th1 cells.MSCs inhibit CD4+ to Th17 differentiation and upregulate PD1 expression by Tregs.The effects of MSCs on T-cells and macrophages promote an anti-inflammatory environment conducive to tumor growth and metastasis.