Control peritoneum and peritoneum prone to endometriosis (within Pouch of Douglas) from women without disease (n = 16) and peritoneum distal and adjacent to endometriosis lesions in women with endometriosis (n = 15) and were analysed for TGF-β expression, reception and signalling by immunohistochemistry, qRT-PCR and a TGF-β signalling PCR array. Here, TGFB1 is linked to endometriosis.