GDF9 and Alzheimer disease: We also noticed that numerous proteins were directly or indirectly associated with or regulated by TGFβ/GDF/BMP signaling (e.g., TGFBR1, FSTL1, THBS1, MMP11, GREM1, GDF3, GDF5, GDF9), making that pathway a lead candidate to test for its involvement in AD.