Increased canonical Wnt signaling in osteogenic cells in myelomatous bones treated with Wnt3a. Myelomatous human bone sections were immunohistochemically stained with 8E7 antibody that reacts with the active form of β-catenin. (A,B) Bones were engrafted with H929/EV (A) and H929/W3A (B) MM cells. Note expression of active form of β-catenin in certain vascular endothelial cells (VECs) and in cellular components along the bone surface. Bones engrafted with H929/W3A had increased numbers of cells expressing the active form of β-catenin along the bone surface. (C,D) Primary myelomatous bones treated with Wnt3a had an increased number of osteoblastic (OB) cells expressing the active form of β-catenin. Osteoclasts (OCs) as well as MM cells expressed very low levels of β-catenin.