Internalization of OPG in CAG cells.

(A) CAG cells incubated on ice for 30 minutes with Alexa Fluor 488–conjugated human OPG (green) shows cell surface binding of OPG. (B-D) Subsequently, the cells were incubated for 1 hour at 37°C, washed, and examined by confocal microscopy. The results show that OPG is internalized, colocalizing (yellow) with the lysosomal marker LysoTracker Red DND-99 (red). Original magnification × 630.