Based on our recent observations that murine PSG23 induces TGFB1 and VEGFA in mouse and human trophoblast cell lines [30] , we explored the possibility that human trophoblasts could also respond to PSG1 treatment. Because we cannot obtain material to perform these experiments with primary first-trimester human trophoblast cells, we relied on the well-characterized, first-trimester extravillous trophoblast (EVT) cell lines HTR-8/SVneo [24] and SGHPL-4 [31] . These cell lines were derived from first-trimester chorionic villous tissue and, after immortalization, have been shown to retain many features of normal EVT and to behave in the same manner as primary cells [32, 33] . HTR-8/SVneo and SGHPL-4 cells were treated with increasing concentrations of PSG1, starting at 1 lg/ml and increasing up to 50 lg/ml. Upregulation of TGFB1 was observed at 10 lg/ml for both cell lines (Fig. 3, A and D) . Significant up-regulation of VEGFA was observed at 30 lg/ml in HTR-8/SVneo (Fig. 3B ) and 10 lg/ml in SGHPL-4 cells (Fig. 3E) .