Effect of GXXYW on cell proliferation in endometriotic lesions. Cell proliferation was evaluated by immunohistochemistry for the expression of proliferating cell nuclear antigen (PCNA). (a) Comparison of the percentage of PCNA+ cells in the different dose groups after 28 days of treatment; 400x Magnification. (b) Box plot showing the percentage of PCNA+ cells. Control group received distilled water only; low dose, GXXYW low-dose group; high dose, GXXYW high-dose group.