Comparison of IL-1β mRNA kinetics in THP-1 cells stimulated with Stx1, LPS, and Stx1 plus LPS. Differentiated THP-1 cells were treated and analyzed as described in the legend to Fig. 1 except that IL-1β and GAPDH cDNA probes were used. (a) Representative Northern blots of Stx1-, LPS-, and Stx1-plus-LPS-induced IL-1β mRNA. (b) Mean intensities of percentage mRNA above basal expression for each time point ± standard errors of the means (error bars) from three independent experiments. Values that are significantly different (P ≤ 0.05) are indicated as follows: +, a significant difference between the values for cells treated with Stx1 and LPS; #, a significant difference between the values for cells treated with Stx1 alone and Stx1 plus LPS.