Having noted that PPARα-/- mice were remarkably sensitive to DEN-induced hepatocarcinogenesis, we examined the relationship of PPARα to the key regulators of cell proliferation and apoptosis in livers from these mice and investigated its tumor suppressive role as well as molecular bases by which PPARα exerts this function in vitro. We studied PPARα downstream effectors using cDNA expression array and confirmed that its direct target was NF-κB by ChIP-PCR. The gene discussed is PPARA; the disease is neoplasm.