Fig. 2.

RA treatment promotes cell growth arrest in human SH-SY5Y neuroblastoma cells. Human SH-SY5Y neuroblastoma cells were grown onto 96-well plates in normal serum for 24 h. Then, cells were subjected to medium replacement containing N: normal serum or L: low serum. Both cultures were supplemented with 15 μM RA as described in “Materials and methods” section. Chronic RA treatment was performed by replacing the corresponding medium with fresh medium supplemented with 15 μM RA every 2 days. On the experimental day 5, SRB assay was performed as described in “Materials and methods” section. Non-RA treated cells (undifferentiated cells) served as controls. Dashed line represents the cell growth at experimental day 0 (n = 24; 0.53 ± 0.02). Data are the mean ± SEM (n = 24) of values from four independent experiments. RA-treated cells were compared to parallel cultures without RA treatment in the corresponding medium (*** P < 0.001 one-way ANOVA)