Fig. 9.

RA treatment (differentiating conditions) abolishes MAPK activation in human SH-SY5Y neuroblastoma cells. Human SH-SY5Y neuroblastoma cells were grown to 80% confluency onto cell culture Petri dishes in normal serum. Then, cells were subjected to medium replacement containing low serum and supplemented with 15 μM RA as described in “Materials and methods” section. Chronic RA treatment was performed by replacing the medium with fresh medium supplemented with 15 μM RA every 2 days. On the experimental day 5, cultures were treated with 300 μM BzATP for the indicated times before analysis. Cells were lysed and a SAPK/JNK and b p38 phosphorylation was determined by western blot analysis of whole-cell lysates. Non-RA treated cells (undifferentiated cells) served as controls. Data are the mean ± SEM of values from three independent experiments. RA-treated cells were compared to parallel cultures without RA treatment (* P < 0.05 one-way ANOVA). Representative gels are shown