Figure 4.

UV irradiation promotes phosphorylation of the MAPK family and c-Jun. Lysates from the NIH 3T3 cells transfected with c-RET (A-H, lanes 2) or RET-MEN2A (A-H, lanes 3; I-L, lanes 4 and 5) and nontransfected control NIH 3T3 cells (A-H, lanes 1) without stimulation (A-H, lanes 1–3; I-L, lanes 4) or 10 min after UV-B irradiation (600 J/m²) (I-L, lanes 5) were subjected to Western blotting with anti-ERK (A), anti-phospho-ERK (E and I), anti-JNK (B), anti-phospho-JNK (F and J), anti-p38 (C), anti-phospho-p38 (G and K), anti-c-Jun (D), and anti-phospho-c-Jun (H and L) antibodies. SDS-PAGE was done in 10% polyacrylamide gels. All measurements were repeated three times with basically the same results. Representative results are provided.