A 50 μl column prepared from 100 nM rEP18 was used to purify the GFP-C/EBP from a crude bacterial extract. Elution was as described for Fig. 4. A, Average epifluorescent measurements from two independent experiments are shown ± standard deviation. B, samples were concentrated, applied to 12% SDS-PAGE, and stained with silver. P, GFP-C/EBP purified by Ni2+-agarose affinity chromatography; C, crude bacterial extract; F, flow-through (unretained) fraction; W1–W10, TE0.1 washes.; -, no sample applied.