Interactions of myeloma cells with osteoclasts promote tumour expansion and bone degradation through activation of a complex signalling network and upregulation of cathepsin K, matrix metalloproteinases (MMPs) and urokinase plasminogen activator (uPA) - Hecht, M; von Metzler, I; Sack, K; Kaiser, M; Sezer, O (Exp Cell Res, 2008)