The tumor growth–promoting effects of opioids are mediated by a signaling cascade involving Akt and extracellular signal–regulated kinase (ERK), whereas their death-promoting effects are mediated by the inhibition of nuclear factor-κB (NF-κB), increased expression of Fas, stabilization of p53, and activation of p38 and c-Jun-N-terminal kinase (39). This evidence concerns the gene TP53 and neoplasm.