Elevated levels of cytokines and growth factors like tumor necrosis factor-α (TNF-α), vascular endothelial growth factor (VEGF) and IL-1, IL-6 and IL-11 found in the serum and respiratory tract of CF patients may stimulate osteoclast-mediated bone resorption and inhibit bone formation [56]. The gene discussed is VEGFA; the disease is cystic fibrosis.