IL6 and neoplasm: Concerning IL-6, it increases bone degradation via: (i) the production of RANKL, and the negative regulation of osteoprotegerin (OPG); (ii) the induction of proteins involved in bone resorption such as PTHrP, interleukin (IL) IL-8, IL-11 and Cox-2; (iii) an increase of oestradiol 17β-hydroxysteroid dehydrogenase activity (an inhibitor of the anti-osteoclast activity of oestrogens); (iv) the stimulation of DKK-1 expression by tumour cells and (v) the downregulation of collagen II and aggrecans by the osteoblasts [31].