To investigate the possible interaction of PSG1 with endothelial cells, we treated primary human myometrial UtMVECs, which have been previously used in coculture experiments to mimic the uterine endothelial lining [34] , with 1, 10, 25, and 50 lg/ml of PSG1 or control protein. In addition, PSG1 and FLAG-Fc were added at the same concentrations to HUVECs and HEEC, immortalized by telomerase-mediated transformation. Significant PSG1-induced secretion of TGFB1 in UtMVECs (Fig. 4A) , HEEC (Fig. 4B ), and HUVEC (not shown) was observed starting at concentrations of 25 lg/ml. When testing the ability of PSG1 to induce VEGFA in these cells, we did not observe a significant induction of VEGFA with concentrations of PSG1 from 1 to 80 lg/ml (data not shown).