SPP1 and endometriosis: Among the molecules identifiedwith aberrant expression during the window of implantation in the eutopicendometrium of women with endometriosis there are receptors of progesterone andestrogen (Young, 2013), integrins (Giudice & Kao, 2004), leukemiainhibitory factor (LIF), glicodelin A, (GdA), osteopontin (OPN),lipolysophosphatidic acid receptor 3 (LPA3), HOXA10 (Revel, 2012), which are related to the establishment ofendometrial receptivity and/or to the interaction between the endometrium andthe embryo (Giudice et al.,2002).