TNF-α induces delayed STAT3 activation in human NPCs.

<p><b>A</b>. Human NPCs were treated with 20 ng/ml TNF-α for 30 min, 6 h, and 24 h. Expression of phospho-STAT3 (P-STAT3) and total-STAT3 (T-STAT3) were detected by Western blotting. β-actin was used as a loading control. <b>B</b>. Human NPCs were treated with 20 ng/ml TNF-α for 30 min, 6 h, and 24 h. Supernatants were collected as NPC conditioned medium (CM). Parallel cultured human NPCs were treated with control NPC-CM or TNF-α-treated NPC-CM (con-CM or TNF-α-CM) for 30 min. Expression of P-STAT3 and T-STAT3 were detected by Western blotting. β-actin was used as a loading control. <b>C</b>. Human NPCs were treated TNF-α-free NPC-CM for 30 min, 6 h, and 24 h. Expression of P-STAT3 and T-STAT3 were detected by Western blotting. β-actin was used as a loading control. <b>D</b>. Human NPCs were treated with 20 ng/ml TNF-α for 30 min or 24 h. Cells were immunolabeled with antibodies for the NPC marker Nestin (green) and P-STAT3 (red). Original magnification is ×60 (scale bar 20 µm). Results are representative of three independent experiments.