Fig. 3. H2O2 pretreatment reduces the activation of both the MKK4 and MKK7 pathways induced by diverse stimuli. (A) U937 cells were incubated in the presence or absence of 0.05 mM H2O2 for 24 hours, followed by a challenge with 1 mM H2O2 for 30 minutes. The SAPK phosphorylation and protein levels (top two panels) and its activity (third panel) were compared. Alternatively, the activities of MKK4 and MKK7 were analyzed 15 minutes after the challenge (bottom two panels). (B) The preincubated cells received the indicated challenges for 30 minutes. The SAPK phosphorylation and protein levels (top two panels), and the SAPK and MKK7 activities (bottom two panels) were analyzed.
