Neither EP1 nor EP2 was expressed differentially to any appreciable degree, whether the comparison was between endometriosis patients and healthy control patients, eutopic and ectopic endometrium in endometriosis patients (Figures 1(a) and 1(b)), endometriosis stages (Figures 2(a) and 2(b)), or the two phases of the menstrual cycle (Table 2). The gene discussed is PTGER1; the disease is endometriosis.