FIG. 6.

Possible involvement of receptor PTKs in UV-induced JNK activation. (A) To investigate the role of EGFR, cells were pretreated with the EGFR inhibitor AG1478 (200 nM) for 20 min or left untreated; they were then stimulated by heat shock (42°C for 1 h), UV-B irradiation (400 J/m²), or EGF (50 ng/ml, 15 min). Cell lystates were prepared and immunoblotted (IB) with an anti-PY antibody. The membrane was stripped and then reprobed with an anti-EGFR antibody. JNK activity was detected by immunoblotting with an antibody specific for p-JNK. Equal loading of samples on each lane was indicated by reprobing the same membrane with an anti-JNK1 antibody. (B) To explore the putative role of c-Met, wild-type (+/+) and Gab1^−/− (−/−) cells were subjected to heat shock (42°C for 1 h), UV-B irradiation (200 or 400 J/m²), or HGF (50 ng/ml) for 5, 10, or 20 min. Cell lysates were prepared and subjected to immunoblotting with the indicated antibodies.