HB‐EGF, COX‐2, and Wnt4 have been implicated in the progression of endometriosis, the abnormal growth of endometrial tissues outside the uterus (Ota et al, 2001; Uno et al, 2010; Arosh et al, 2015; Miller et al, 2015). The gene discussed is PTGS2; the disease is endometriosis.