Fig. 3. Quantitative analysis of unconventional secretion of FGF-2-GFP and FGF-2-GFP-DHFR fusion proteins in living cells based on FACS. CHO_FGF-GFP (A,B), CHO_{FGF-2-GFP-DHFR} (C,D) and CHO_MTS-GFP-DHFR cells (E,F) were grown in the absence (grey curves) or presence (green curves) of doxicycline. Cells were dissociated from the culture plates using a protease-free protocol followed by immunostaining using either affinity-purified anti-GFP (A,C,E) or monoclonal anti-His-tag antibodies (B,D,F). Living cells were analysed simultaneously for both total GFP fluorescence and cell-surface staining employing a BD FACSCalibur system.