PCNA and endometriosis: Additionally, M2 macrophages can suppress expression of antitumor cytokine IL-24 and its receptor on endometrial stromal cells, thereby enhancing proliferation and invasion of the latter (through increased markers Ki-67, proliferating cell nuclear antigen [PCNA], COX-2, and decreased CD82 suppressor levels)—this mechanism also contributes to endometriosis development (50).