DIE lesions also exhibit increased SK1, S1P3 and S1P5 mRNA levels and the expression of a specific S1P transporter, Spns2, responsible for the extracellular release of S1P, is altered only in DIE, further highlighting the dysregulation of S1P signalling in the different forms of endometriosis [15] (Fig. 2). The gene discussed is MBTPS1; the disease is endometriosis.