Fig. 10. Effects of UV on signal proteins downstream of EGFR. Cells were either left untreated or treated with 10, 50 or 200 J/m² UV, or 5 nM EGF, and incubated for the indicated time intervals (minutes). The cell lysates were subject to SDS-PAGE and western immunoblotting with antibodies to the indicated proteins. (A) The cells were pretreated with PD153035 or left untreated as indicated, before stimulation with UV or EGF. Anti-Raf1 displayed no mobility shift for Raf in UV-exposed cells, in contrast to that seen in EGF-stimulated cells. The EGF-induced mobility shift for Raf1 was inhibited by treatment with PD153035. Anti-pMEK showed a UV-induced MEK-activation, that was not inhibited by treatment with PD153035. By contrast, PD153035 inhibited the EGF-induced MEK-activation. (B) Cells were treated with increasing doses of UV, and incubated for the indicated time intervals (minutes), before immunblotting. MEK and ERK showed activation 20 minutes after irradiation (pMEK and pERK, respectively). Anti-EGFR was used to identify the protein levels in the different samples. C, control cells. The molecular weight markers presented at the left indicate 220 kDa.