Figure 2. Proposed scheme of mechanisms leading to trophoblast invasion into the decidua by HGF (hepatocyte growth factor) produced by human placental multipotent mesenchymal stromal cell (hPMSC) in villous mesenchyme. Hypoxia reduced HGF expression by hPMSCs. HGF produced by hPMSCs were able to interact with c-Met receptor on trophoblast and induce the trophoblast 3′,5′-cyclic adenosine monophosphate (cAMP) expression. The cAMP activates PKA (protein kinase A), which in turn, activates Rap1 leading to integrin β1 activation. However, the response of Epac-1 and Epac-2 (exchange protein directly activated by cAMP-1 and -2) to HGF stimulation in trophoblasts is not clear.