Nevertheless, endothelin-1 (ET-1), which is encoded by the EDN1 gene, has been associated with endometriosis pathogenesis, as the cystic fluid of endometriomas contains a higher amount of ET-1 compared to ovarian cysts other than endometriomas, and in vivo experiments in mice demonstrated that blocking ET-1 activity was effective in decreasing endometriosis-related pain [28]. This evidence concerns the gene EDN1 and endometriosis.