Negatively regulates TGF-beta signaling. High expression in kidney medulla, placenta and spleen; low in kidney cortex, liver, prostate and gut. Not expressed in normal skin, expression is high in melanocytes and in 3 out of 11 melanoma metastases tested. Expression in poorly metastatic human melanoma cell lines; no expression in highly metastatic human melanoma cell lines. Belongs to the BAMBI family.