Myeloma cells could promote osteoclast formation directly via endogenous expression of RANKL, tumor necrosis factor alpha (TNF-α), and macrophage inflammatory protein 1 alpha (MIP-1α) By endogenous expression of RANKL, tumor necrosis factor alpha (TNF-α), and macrophage inflammatory protein 1 alpha (MIP-1α), myeloma cells could promote osteoclast cell growth [106,107]. Here, TNF is linked to plasma cell myeloma.