ATF2 knockdown reduces basal and TNF-α–induced expression of proatherogenic genes. Total cell mRNA and protein were harvested from HUVECs that were untransfected (control) or transfected with nonspecific (siNS) or ATF2 siRNA (siATF2). (A) ATF2 mRNA expression levels represented relative to ribosomal protein P0, as measured by real-time PCR. (B) Total ATF2 protein levels were measured using Western blot, and equal loading was verified with α-tubulin. (C) These protein levels were quantified as ratios versus siNS, corrected for α-tubulin. (D) Inhibition of basal and TNF-α–induced expression of genes from cluster groups A and B by knockdown of ATF2 compared with a nonspecific control. ATF2 expression was inhibited by siATF2 during both vehicle and TNF-α treatment (i), resulting in reduction of basal and TNF-α–induced expression of SELE (ii), CCL2 (iii), IL-8 (iv), VCAM1 (v), and EDN1 (vii) but not PAI-1 (vi). Represented are the mean P0-corrected relative mRNA expression levels from 3 different HUVEC isolates measured in duplicate by RT-PCR. Error bars indicate SEM. Significant difference versus nonspecific siRNA is indicated (*P < .05; **P < .01).