Prostaglandin E2 (PGE2) promotes the infiltration of M2-type macrophages in non-small cell lung cancer (NSCLC) tissues through PGE2 receptor 4 subtype (EP4); the EP4 inhibitor E7046 has been shown to block this effect and reduce tumor growth rates and vascular density (74). The gene discussed is PTGER4; the disease is neoplasm.