Luciferase assay
For transient transfection of A3.01 and U937 cells, DMRIE-C transfection reagent (Life Technologies) was used (36). Cells were seeded in 6-well tissue culture plates (5 x 105 cells per well) in 1.5 ml Opti-MEM (Life Technologies) containing 0.5 microg firefly luciferase reporter plasmid and 3.5 microl DMRIE-C. After 4-5 h of incubation, 1.5 ml complete RPMI medium were added. HepG2 and Huh7 cell lines were transfected using LipofectAMINE Plus as recommended by the manufacturer (Life Technologies). Briefly, exponential growing cells (1.5 x 106) were transfected with 5 microl LipofectAMINE, 6 microl PLUS reagent and the required amount of plasmid DNA in a final volume of 1 ml Opti-MEM. Following 4 h of incubation, cells were washed in PBS and 3 ml of complete DMEM medium were added. 
For cotransfection of reporter plasmids and siRNA into HeLa cells, HiPerfect transfection reagent (Qiagen) was used according to the manufacturer's protocol for cotransfection of adherent cells with siRNA and plasmid DNA. 
Two days after transfection of the respective cell lines, cells were harvested in 100 microl (suspension cells) or 300 microl (adherent cells) of Passive Lysis Buffer (Promega) and luciferase assay was performed using the Dual Luciferase Assay System (Promega) according to the manufacturer's instructions. As an internal control, 50 ng (adherent cells) or 100 ng (suspension cells) of ph-RG-TK plasmid (Promega), which constitutively expresses renilla luciferase was cotransfected in every sample and firefly luciferase activities were normalized to renilla luciferase activities. Mean values (+/-SD) of a representative experiment performed in triplicate are shown in the figures. For stimulation of cells, final concentrations of 20 ng/ml TPA (Sigma) or 30 ng/ml IFN-alpha or 30 ng/ml IFN-gamma (Tebu-Bio) were applied approximately 15 h before harvesting for luciferase assay. 
