Characterization of an fENL producer cell line. (A) Detection of flagENL expression by immunoblot. Extracts from transduced 293fENL and HEK293 parental cells were tested for endogenous and ectopic ENL expression by probing with anti-ENL and anti-flag antibodies. Actin served as loading control. A densitometric quantification of the relative expression levels is shown in the bar graph. (B) Gel filtration on Sephacryl S300. Extracts from 293fENL cells were separated by gel filtration on a precalibrated column as indicated. Individual eluate fractions were tested by immunoblotting with antibodies against ENL and flag. The elution profile of ENL from the parental HEK293 cells is shown in the bottom panel.