Figure 1.

The proliferation inhibition of U937 cells, irradiated by different colored light emitting diodes (LED) arrays with wavelengths centered at 456 nm (blue), 515 nm (green), 630 nm (red), and 840 nm (near infrared) for 12 and 24 h, without incubation. The cell viabilities are evaluated using Cell Counting Kit-8 assay (CCK-8) assay for 4 h, and the absorbance values are measured at 450 nm. Data shown are the mean values ± SD of at least three independent experiments. * p < 0.05 vs. control group. The cells treated under dark conditions is set to control group.