Figure 3.

Expression of sphingosine kinase (SphK) 1 (a) and 2 (b) in photoreceptor cells detected by the quantitative polymerase chain reaction normalized to the housekeeping gene of glyceraldehyde-3-phosphate dehydrogenase (GAPDH). 661W cells were exposed to a light-emitting diode with various intensities (800 lux, 8000 lux, and 40,000 lux) (n = 6, each group). Each column represents the mean ± standard error. Statistical analysis was performed using Dunnett’s test. * Significant p-values are labeled with p < 0.05. n.s: not significant.