As shown in Fig. 2a, exposure of mouse M-CSF generated osteoclast precursors to conditioned medium from breast cancer cells MDA-231 and 4T1 (20% v/v) enhanced RANKL-induced osteoclast formation (p < 0.001), and these effects were significantly reduced by the selective IKKβ inhibitors IKKβIII or IKKβV (3 μM). The gene discussed is TNFSF11; the disease is breast cancer.