POU5F1 and neuroblastoma: To investigate the effect of different concentrations of melatonin on Sox2, Oct4, and Nanog expression levels in human neuroblastoma SH-SY5Y cells, cells were treated with varying concentrations of melatonin (0.01, 0.1, 1, 10 μM, and 0 μM for controls) for 24 h, and protein expression levels were determined using Western blotting.