CD4 and neoplasm: Moreover, PGE2 in the TME elicits a wide range of biological effects associated with immunopathology in inflammation and cancer; for instance, PGE2 excretion from tumor cells is critical for M2-type polarization and infiltration of macrophage [192]; PGE2 can suppress the activation of CD4+ and CD8+ T cells and leads to dysfunction of T cells [193], and PGE2 derived from CRC and MDSCs exacerbates the immunosuppressive activity of MDSCs and accelerated tumor growth of CRC [194].