siPML down-regulates TRAIL. (A) RNAi silencing of PML inhibits induction of TRAIL protein by IFN-α. The 8226 cells transfected with siluc or siPML were treated with IFN-α 500 U/mL for 48 hours and analyzed for TRAIL protein expression by immunoblotting. GAPDH protein level serves as loading control. (B) RNAi silencing of PML inhibits induction of TRAIL mRNA by IFN-α. RT-PCR of cells treated as in panel A using primers specific for TRAIL and GAPDH as a control.