Figure 1. Fenretinide treatment induces a neuronal-like phenotype in ARPE-19 cells. Cells were treated on uncoated tissue culture plastic with media containing dimethyl sulfoxide (A) or 3 μM fenretinide (FR; B) once a day for 7 days, and the morphology was examined by phase microscopy. C: Scanning electron microscopy of FR-treated cells shows neural processes and the formation of varicosities and neurites (highlighted in the dashed boxes and shown at high magnification in D and E, respectively). F: Synaptic-like appositions were also present at the neurite terminal, shown at high magnification in G. Scale bars equal 200 μm in A and B, 100 μm in C, 4 μm in D, 20 μm in F, and 2 μm in E and G.