Protein expression analysis of Flag-Bcl-2 and Flag-Bcl-XL in FL5.12 clones. (A) Immunoblot analysis of FL5.12 clones. Cell lysates from FL5.12 clones expressing Flag-Bcl-XL or Flag-Bcl-2 were electrophoresed through 12.5% SDS-polyacrylamide gels, transferred to nitrocellulose and incubated with anti-Flag MoAb (1 μg/mL). Relative ratios of Flag:β-tubulin protein expression determined by densitometric measurements following immunoblot analysis with anti-β–tubulin MoAb (clone TUB 2.1). Note that the Neo control does not contain Flag-Bcl-2 or Flag-Bcl-XL. The reaction was developed by enhanced chemiluminescence. (B) Fluorescence histograms of FL5.12 clones. Cell clones expressing Flag-Bcl-XL or Flag-Bcl-2 were analyzed for Flag-epitope expression by flow cytometry. Cells were stained with anti-Flag MoAb (1:50 dilution) and counter-stained with fluorescein isothiocyanate-conjugated Fc-specific antimouse IgG (1:50 dilution). Controls are FL5.12 clones expressing Flag-Bcl-XL (clone 14) or Flag-Bcl-2 (clone 1) stained with isotype-matched control IgG1 MoAb and counter-stained as above.