Figure 1. ARPE-19 cells develop RPE phenotype characteristics during differentiation. ARPE-19 cells were grown for various time periods as outlined in the Methods section, and the morphology of the cells was examined with phase-contrast microscopy. A: Subconfluent cells 1 day after plating. B: Cells grown for 4 days. C: Cells grown for 4 weeks. D: Cells grown for 4 months. Magnification, 100X.