CD4 and neoplasm: Interestingly, PGE2 has been shown to regulate the function of various immune cells within the tumor microenvironment (TME), including myeloid-derived suppressor cells (MDSCs), dendritic (DC) cells, natural killer (NK) cells, CD4 and CD8 T cells, resulting in immune evasion (Zelenay et al., 2015; Böttcher et al., 2018; Bonavita et al., 2020).