(A) MDMs (n=4) were transfected with scrambled, ATF4, C/EBPα, Runx1 or Runx2 siRNA for 24h. Fold mRNA expression normalized to scrambled, siRNA-transfected MDMs + SEM. (B) MDMs (n=4) were left untreated (for acute) or pre-treated with 100μg/ml MDP for 24h, then transfected with scrambled or a combination of Twist1 and Twist2 siRNA + ATF4, C/EBPα, Runx1 or Runx2 siRNA, alone or in combination, and 24h later (total 48h MDP pre-treatment), MDMs were stimulated with 100μg/ml MDP for 24h (acute) and cytokine secretion was assessed. Numbers on the bars are the ratios of cytokine secretion upon MDP treatment of pre-treated versus the corresponding non-pretreated MDMs. Significance comparisons are between MDP treatment of pre-treated, Twist1/2 siRNA-treated cells relative to the same condition in combination with siRNA to each of the transcriptional activators or as indicated. *, p<0.01; **, p<0.01; ***, p<0.001; †, p<1×10−4. Tx, treatment; scr, scrambled.