SFRP4 and adenomyosis: In ectopic endometrium of adenomyosis, the expression levels of COX-2 were positively correlated with the expressions of WBP2, IFITM3, and SFRP4 (r = 0.536, P < 0.01; r = 0.591, P < 0.01; r = 0.533, P < 0.01; Figs. 3A–3C).