Antibody specificity and presence of the SERPINE2 protein in human uterine fluid. (A) Four hundred nanograms of recombinant human SERPINE2 was resolved on 10% SDS-PAGE and followed by Western blotting using anti-mouse SERPINE2 antiserum (lane 1), an anti-human SERPINE2 antibody (R&D) (lane2), or another anti-human SERPINE2 antibody (Abnova) (lane 3). (B) One hundred micrograms of the extract of endometrial curettage was analyzed by anti-mouse SERPINE2 antiserum (lanes 1 and 2) and an anti-human SERPINE2 antibody (R&D) (lanes 3 and 4). (C) Fifty micrograms of uterine fluid proteins collected from each individual patient (n = 7) was Western-blotted using anti-mouse SERPINE2 antiserum (1:3000) (upper panel). EP, MP, and LP indicate early-, mid-, and late-proliferative phases, and ES and MS indicate early- and mid-secretory phases, respectively. The blot was also overexposed to clearly display the staining signal (lower panel).