Figure 3. CNGB3 F525N mutation impairs cell viability with CPT-cGMP treatment. Transfected 661W cells were treated with or without 0.1 μM CPT-cGMP for 24 h. After treatment, cells were labeled according to the LIVE/DEAD assay protocol: vital cells were stained by calcein AM and show green fluorescence (A, C, E, and G); damaged cells were penetrated by ethidium homodimer and show red fluorescent nuclei (B, D, F and H). Fluorescent images were obtained using a Zeiss LSM 510 confocal laser-scanning microscope as described in the Methods section.