Figure 6.

TRAIL-mediated activation of ERK1/2 is responsible for the induction of proliferation. A) SGBS preadipocytes were stimulated with growth medium alone or with TRAIL. At the indicated time points, proteins were isolated and subjected to Western blot analysis to assess the activation state of the ERK1/2, p38, and JNK pathways. β-actin was used as a loading control. “C” indicates a positive control. One representative of 3 independent experiments performed is shown. B, C) SGBS preadipocytes were stimulated with growth medium alone or with TRAIL in the absence or presence of different doses of PD0325901 or AZD6244. B) At the indicated time points, proteins were isolated and subjected to Western blot analysis to assess the inhibition of ERK1/2 activation by PD0325901 or AZD6244. α-tubulin was used as a loading control. One representative of 3 independent experiments performed is shown. C) After 72 hours, [³H]-thymidine incorporation was measured. Data are expressed as means ± sem of 3 independent experiments performed. **P ≤ 0.01; ***P ≤ 0.001 compared with growth medium alone (directly above the bars) or comparing the indicated treatments (above the connecting line). D) SGBS preadipocytes were stimulated with growth medium alone or with TRAIL in the absence or presence of cycloheximide (CHX) or different doses of PD0325901 or AZD6244. After 48 hours, apoptotic cell death was measured by flow cytometry and specific apoptosis was calculated. Data are expressed as means ± sem of 3 independent experiments performed. *P ≤ 0.05; **P ≤ 0.01; ***P ≤ 0.001 compared with growth medium alone (directly above the bars) or comparing the indicated treatments (above the connecting line).