Fig. 2. Characterization of the various model cell lines based on confocal microscopy. CHO_FGF-2-GFP (A-C), CHO_{FGF-2-GFP-DHFR} (D-F) and CHO_MTS-GFP-DHFR cells (G-I) were grown on coverslips in the absence (panels A,D,G) or presence of doxicycline (panels B,C,E,F,H,I). Cells were fixed without permeabilization using paraformaldehyde followed by immunostaining using affinity-purified anti-GFP antibodies. In B, E and H total GFP fluorescence is shown, whereas in panels C, F and I cell-surface staining is shown.