Oxidative Stress Posttranslationally Regulates the Expression of Ha-Ras and Ki-Ras in Cultured Astrocytes
Figure 5
Activation of the MAPK pathway is required for the late reduction in Ha-Ras expression in cultured astrocytes challenged with hydrogen peroxide. Immunoblot analysis of phosphorylated ERK1 and ERK2 in cultures exposed to hydrogen peroxide for 5, 30, or 60 min is shown in (a). The experiment was repeated twice with identical results. Immunoblot analysis of Ha-Ras and Ki-Ras in pan-Ras immunoprecipitates from cultures pretreated for 15 min with the MEK inhibitor, PD98059 (25 M), and then challenged with hydrogen peroxide for 30 or 60 min is in (b). Values are expressed as per cent of controls and represent the means ± SEM of 4 determinations. * (Student’s t test) versus the respective value obtained in the absence of PD98059. Values at 5 min with hydrogen peroxide alone are also shown for comparison.
