SRI and Infertility: To validate the observed protein abundance changes between early-secretory (LH+2) and mid-secretory phase (LH+7) endometrium from infertile women, immunohistochemistry of Sorcin, Cofilin-1, Ran GTP-binding nuclear protein (Ran) and Apo-A1 were carried out on individual endometrial biopsies following fixing in formalin.