HIF1A and endometriosis: We analysed the expression of HIF-1α, a key regulator of hypoxia, and 8-hydroxy-2-deoxyguanosine (8-OHdG), an OS-induced DNA damage marker, in normal endometria, eutopic endometria and ectopic lesions from endometriosis patients and healthy controls using immunohistochemistry (Fig. 1a).