Characterization of enriched scFv C1-N1N2. A: scFv from crude extract was purified on Ni-NTA beads. Fractions (20 μl) were resolved on a 12.5% SDS-PAGE gel, and visualized by Coomassie Blue staining. Crude: total extract; flush: non bound scFv; El (1–4): elution fractions 1 to 4. B: Each step of purification (1:10 diluted elutions in 3% milk-PBS) was analyzed for binding to GST-RhoA and GST-RhoAQ63L protein immobilized on an ELISA plate. Bound scFv were detected with horseradish peroxydase-labeled anti-myc using TMB as substrate. Results are expressed as absorbance at 480 nm. Graphs are representative of more than 5 experiments, each performed in duplicate.