DKK1 and neoplasm: Taken together, these studies suggest a scenario in which DKK1 has a dual, stage depend, role: whereas high DKK1 expression in early MM contributes to a tumor permissive micronenviroment within the BM, advanced MMs that have acquired BM independence may benefit from DKK1 loss, which enhanced Wnt signaling and thereby promotes MM growth and dissemination.