Fig. 1. UV-exposed cells did not show increased EGFR tyrosine phosphorylation. Tyrosine phosphorylation was analysed in whole cell lysates (A) and EGFR immunoprecipitates (B) subject to SDS-PAGE and western immunoblotting with rabbit anti-pY992, pY1068, pY1086, pY1148 and pY1173. Cells were either left untreated or exposed to the indicated UV-doses and chased for the indicated time intervals (minutes). The whole cell lysates (A) were also analysed for tyrosine phosphorylation with a general anti-phosphotyrosine antibody (4G10; pTyr). The total levels of EGFR, determined with anti-EGFR antibodies, are shown (bottom line). Cells stimulated with 5 nM EGF for 5 minutes were used as a positive control. C and E denote control and EGF-stimulated cells, respectively, and J denotes J/m². The molecular weight markers presented at the left indicate 220 kDa.