Osteoblasts and osteoclasts secrete TGF-β, IL-6, IL-8, MCP-1, VEGF, IL-1B, cathepsin K, macrophage inflammatory protein 2 (MIP-2) and resistin [114], and breast cancer cells increase the secretion of IL-6, MCP-1 and IL-8 from osteoblasts [115] and also increase the secretion of IL-8, IL-6, MCP-1, MIP-2 and VEGF [116]. The gene discussed is CTSK; the disease is breast cancer.