Effects of NonO and hnRNP-K on TNF-α–mediated P4Hα1 promoter suppression. A, Expression of NonO or hnRNP-K siRNA was silenced by transfection with NonO- and hnRNP-K–specific siRNAs at the same time that pGL3-P4Hα1 promoter vectors were transfected to HASMCs. Twenty-four hours after the transfection, cells were treated with or without 100 ng/mL TNF-αfor 8 hours. Luciferase mRNA levels measured by real-time RT-PCR were used to evaluate the effects. B, Expression of NonO or hnRNP-K was silenced by specific siRNA in HASMCs with no simultaneous pGL3 transfection. Twenty-four hours after the siRNA transfection, HASMCs were treated with or without 100 ng/mL TNF-αfor 8 hours. The levels of P4Hα1 mRNA were measured and compared among different conditions. ANOVA was used for comparisons among groups, and Bonferroni post hoc analysis was used to test between-group differences. **P<0.01 for TNF-αtreatment vs all other conditions except cells treated with TNF-α+hnRNPk siRNA. There was no statistical difference between controls and cells treated with NonO siRNA alone, TNF-α+NonO siRNA, and hnRNPK siRNA alone.