PTGER4 and neoplasm: In addition to determine M2 polarization, PGE2 also dampens macrophage cytotoxicity against tumor cells [129], suppresses cytokine production [130], increases TAM infiltration in gastrointestinal tumors [131], by activating the EP1 receptor [132], and stimulates monocyte differentiation toward immunosuppressive monocytic MDSC (M‐MDSC) through EP4 [128].