TGFB1 and sarcoma: BMP and TGF-β signaling are required for osteoblast and chondrocyte differentiation,17, 20, 21, 41 but bone invasion and osteolysis in ES are also associated with enhanced β-catenin signaling.42, 43 We observed downregulated BMP, TGF-β and β-catenin signaling at late development in EFPrx1 embryos, but high β-CATENIN expression was seen when sarcomas formed.