The overexpression of PTGIS, functioning to convert prostaglandin H2 (PGH2) to prostaglandin I2 (PGI2), whose higher expression in the peritoneal fluid was observed in patients with endometriosis (Ylikorkala et al., 1984), had also been found a previous study (Monsivais et al., 2012). Here, PTGIS is linked to endometriosis.