FIG. 5.

Effects of Stx1 and/or LPS on TNF-α mRNA stability in THP-1 cells. Differentiated THP-1 cells (5 × 10⁶ cells/ml) were treated with LPS (200 ng/ml) for 1 h, Stx1 (400 ng/ml) for 2 h, or LPS plus Stx1 for 2 h. ActD was then added to each plate at a final concentration of 5.0 μg/ml. Total RNA was isolated at each of the indicated time points after ActD addition. Northern blot analysis was performed, and TNF-α mRNA was detected and quantitated using a PhosphorImager. (a) Representative Northern blots probed with ³²P-labeled TNF-α- and GAPDH-specific cDNA probes. (b) Mean log intensities of percent TNF-α mRNA remaining ± standard errors of the means (error bars) from three independent experiments. Values that were significantly different (P ≤ 0.001) are indicated as follows: *, a significant difference between the values for cells treated with Stx1 plus LPS and LPS alone; #, a significant difference between the values for cells treated with Stx1 and LPS.