FIG. 7.

MEK inhibitor PD98059 blocks UV-stimulated ERK2 activation and impairs induction of c-Jun and AP-1. (A) Logarithmically growing NIH 3T3 cells were pretreated or not (control [Con]) with 50 μM MEK inhibitor PD98059. After an incubation period of 30 min, cells were UV irradiated (40 J/m²). Ten minutes after irradiation, cells were harvested for determination of activation of ERK2 and JNK1, as described in Materials and Methods. Shown are the autoradiograms. (B) Pretreatment with PD98059 and subsequent UV irradiation of cells were performed as described for panel A. After an incubation period of 4 h in the presence of PD98059 (50 μM), cells were harvested for Western blotting (c-Jun) and AP-1 binding analysis (AP-1). The autoradiograms are shown.