Based upon the aforementioned evidence, the endometriosis inflammatory process is thought to be induced by estradiol and mediated by estrogen receptor β (ERβ) (Takayama et al., 1998; Monsivais et al., 2014; Chandler et al., 2015; Monsivais et al., 2016), and correlates with the estrogen receptor (ER) expression levels (Bukulmez et al., 2008). This evidence concerns the gene ESR2 and endometriosis.