The ability of EBF and E47 to act synergistically on the λ5 promoter is abolished by expression of Notch1-IC. (A) The diagram shows the relative luciferase activity obtained after transiently transfecting HeLa cells with 40 ng of the λ5 reporter plasmid and 120 ng of the EBF and/or 120 ng of the E47-encoding expression plasmid, along with 40 or 120 ng of the Notch1-IC expression plasmid. (B) Graphs display the resulting relative activity of a λ5 reporter plasmid in HeLa cells after activation by ectopic expression of a forced dimer of E47 in the presence of increasing amounts of cotransfected Notch1-IC plasmid as indicated. (C) Columns representing the relative luciferase activity observed after cotransfecting 40 ng CD19 reporter construct and 200 ng Pax-5 alone, or together with 120 ng Notch1-IC, into HeLa cells. Reporter activities were normalized to the internal control pRL-0, and values obtained with 320 ng empty expression plasmid were set to 1. Data were calculated from a single representative of 3 experiments with 3 transfections. Error bars indicate SD.