Figure 5: Determination of p53 expression following exposure to 0.5 ppm CH3Hg+ or 0.5 ppm HgCl2. MCF-12A cells exhibited the greatest increase in p53 expression following exposure to CH3Hg+, yet exposure to HgCl2 resulted in a net reduction in p53 expression suggesting that the chemical form of mercury is important for altering p53 expression (F2,18=15.48; p<0.0001). In addition, cell type was a factor in the response to mercury (F2,18=19.96; p<0.0001). In both MDA-MB-453 and MCF-7 cells, exposure to either the organic or inorganic form of mercury resulted in a reduction in p53 expression. These reductions only reached significance in the MDA-MB-453 cell line. Data were analyzed by one-way ANOVA (treatment X cell line) followed by Dunnett’s test for multiple comparisons to control (0 ppm) mean for each cell line. Data are expressed as mean ± SEM of N=4 in duplicate.