TNF and breast cancer: In contrast, we found no evidence to suggest that IKKβ in human osteotropic breast cancer cells or in osteoblasts regulate the expression of Parathyroid hormone-related protein (PTHrP), tumour necrosis factor alpha (TNFα), transforming growth factor beta (TGFβ), and Interleukin 6 (IL6) (data not shown), which all have been previously implicated in the regulation bone cell differentiation and activity [1, 2].