Following standard protocol, we stained the cells with tartrate-resistant acid phosphatase (TRAP), and we confirmed that adding the CM of MSCs cocultured with myeloma cells enhanced TRAP+ cell numbers and osteoclast-associated gene expression comparing to those with addition of MSC CM, while knockdown of integrin α6 in myeloma cells reduced such effects (Figures 3D, E). This evidence concerns the gene ACP5 and plasma cell myeloma.