Figure 1. UVB radiation up-regulated the expression of GPNMB.

(A) PIG1 melanocytes were exposed to a dose of 20 mJ/cm² UVB radiation and cultured for the indicated times. The mRNA expression levels were determined using real-time quantitative PCR, and were normalized based on the β-actin levels. Data were represented as relative mRNA expression levels, which were the ratio of normalized mRNA expression levels of UVB-irradiated samples to those of non-UVB-irradiated samples. (B) PIG1 melanocytes exposed to a dose of 20 mJ/cm² of UVB radiation were harvested and lysed after the indicated incubation times. Western blotting was performed to examine protein expression of GPNMB. The expression levels of GPNMB were normalized based on the β-actin levels. Densitometric data were represented as mean±SEM in triplicate. *p<0.05. (C) Double immunofluorescence was performed with anti-Tyr antibody (green) to detect melanosomes and anti-GPNMB antibody (red) to identify the expression of GPNMB. Nuclear stained with DAPI (blue) were introduced for visualization purposes. Fluorescence was observed and analyzed with a fluorescence microscope. Left: Tyr staining (in green); Middle: GPNMB staining (in red); Right: merged (in yellow).