IDO1 and endometriosis: Therefore, the level of Ki-67 in MRC2-silenced ESCs increased compared with that in the vector group (Figures 5e and f), which is consistent with the notion that ectopic ESCs have a stronger ability for proliferation.6 Similarly, the expression of Ki-67 and IDO1 also increased in ectopic lesions after MRC2 shRNA was intraperitoneal injected to the peritoneal cavity of endometriosis mice model in vivo (Figures 5h and i).