USAG1, also known as WISE, Ectodin, or SOSTDC1, is a secreted glycoprotein of the sclerostin family. It binds and sequesters BMP-2, -4, -6, and -7, and it blocks LRP5 and LRP6 interaction with Wnt proteins. USAG1 co-localizes with BMP-7 in the developing and adult kidney, particularly in distal tubule epithelial cells. It is also found in ectodermal tissues such as tooth ameloblasts, osteoblasts, cells of the dermal papilla, mammary placode epithelium, and uterine lumenal epithelium. USAG1 coordinates BMP, Wnt, FGF, and Shh signals to regulate apoptosis during tooth and bone development.