TNF and neoplasm: The main mediators known to influence expression of polyubiquitin genes and proteasomal subunits are glucocorticoids (Wang et al, 1998), cytokines such as tumour necrosis factor-α (TNF-α) (Li et al, 1998) and proteolysis-inducing factor (PIF) (Lorite et al, 2001), a sulphated glycoprotein produced by cachexia-inducing murine and human tumours (Todorov et al, 1996), which specifically induces degradation of skeletal muscle (Lorite et al, 1998).