SMAD3 and spontaneous abortion: To further validate this signaling, we overexpressed or silenced TGFβ2 in human trophoblast Swan 71 or HTR‐8/SVneo cells (Figure S1D,E, Supporting Information), which have been widely used as cell models in various miscarriage studies.[36, 39, 40, 48] TGFβ2 overexpression up‐regulated, whereas TGFβ2 knockdown down‐regulated, the protein levels of TGFβR2, Smad3, and pSmad3 in Swan 71 or HTR‐8/SVneo cells (Figure 1M,N; Figure S1F,G, Supporting Information).