However, HF concentrations required to inhibit TGFβ signaling in epithelial cells are substantially higher (>100 nM) than concentrations shown to have biological consequences at the level of gene expression (1-10 nM) or HF plasma levels in animal models where HF exhibited biological activity (4 nM -10 nM) [2,4,5,14]. Here, TGFB1 is linked to hydrops fetalis.