Figure 4: (A) Immunocytochemical detection of the Nitrotyrosine after 6 hours. The semiquantitative analysis of immunocytochemical staining of Nitrotyrosine in the Pb-treated cells (100 μM) compared to control (each group: n=100 cells). Comparisons of the mean gray values of the immunocytochemistry analyses were performed with the use of one-way ANOVA. The Pb treatment led to a significant increase of Nitrotyrosine, *p<0.05. (B) Immunocytochemical detection of 8-isoprostane after treatment with Pb (100 μM) for 6 hours. The plots of the arbitrary gray value of the immunocytochemical staining for 8-isoprostane, shows significant enhancement of this protein (p<0.0001) under the Pb treatment. Comparisons of the mean gray values of the immunocytochemistry analyses were performed with the use of one-way ANOVA. The left side of the figure shows exemplary photomicrographs of immunocytochemical-stained HaCaT cells exposed to 100 μM Pb or with H2O (as solvent of Pb) for 8-isoprostane (Magnification=500 fold; Bars=10 μm).