May have regulatory role in cell division or differentiation in response to extracellular signals. Interacts with CPNE4 (via VWFA domain) (PubMed:12522145). Interacts with SMAD2, SMAD3 and RNF111. Interacts with WWP1 (By similarity). Ubiquitinated by RNF111 and RNF165, promoting proteasomal degradation, leading to enhance the BMP-Smad signaling. Belongs to the SKI family.