Fig. 4. UV-exposure induces EGFR mobility shift. (A) Cells were either left untreated (lane 0) or exposed to 200 J/m² UV (lanes 1,3) or 5 nM EGF (lanes 2,4), and incubated for 1 hour (lanes 1,2) or 2 hours (lanes 3,4). Cell lysates were subject to SDS-PAGE and western immunoblotting with anti-EGFR. Unstimulated cells were used as controls. (B) Cells were either left untreated, or exposed to 200 J/m² UV or 5 nM EGF, and incubated for 10 minutes before immunoprecipitation with anti-EGFR. The immunoprecipitates were incubated in DEA buffer with or without alkaline phosphatase (AP). The immunoprecipitates were subject to SDS-PAGE and western immunoblotting with either anti-pY1173 or anti-EGFR. EGFR immunoprecipitates from unstimulated cells were incubated in DEA buffer and used as controls. C, control cells. The molecular weight markers presented at the left indicate 220 kDa.