Tumor cells produce hormones and growth factors such as parathyroid hormone-related peptides (PTHrP), receptor activator of nuclear factor kappa B (NFκB) ligand (RANKL), granulocyte-macrophage colony stimulatory factor (GMCSF), IL-1, IL-6, and MIP-1α, which activate various bone cells such as osteoblasts and osteoclasts and disrupt the homeostatic balance in cancers such as breast and prostate cancer. The gene discussed is IL1B; the disease is cancer.