Fig. 1.

RA-induced neuronal differentiation of SH-SY5Y cells. Cells were treated with 10-μm RA in 1% fetal bovine serum-culture medium for 5 days. (A) Representative phase contrast images. White boxed areas indicate magnified images shown on the right of each day. The arrow indicates neuritic extension. Bar = 40 μm. (B) Immunofluorescence staining with Hoechst33258 nuclear staining (blue) and the neuronal marker MAP2 (red). The arrow indicates a MAP2-positive cell. Bar = 50 μm. Imaging results are representative of 3 independent experiments. (C) Quantification of mean fluorescent intensity of MAP2-positive cells. Data are expressed as mean ± SD. (D) Immunoblots of MAP2 expression and band quantification were obtained from 3 independent experiments. The density of the bands was normalized with that of α-tubulin. Data are expressed as mean ± SEM of percentage to the control. ^*P < 0.05 indicates a significant difference in comparison with day 0 which was considered the control group; ^##P < 0.01 implies the difference between designated groups. RA, Retinoic acid; MAP2, microtubule-associated protein 2.