Figure 6.

BHLHB1 inhibits E2A-induced transactivation. (A) NIH 3T3 cells were transfected in triplicate with the indicated vectors. TATA-luc and E(2,5)-Luc are luciferase reporter vectors, pCAT is the pCATControl vector used to control for transfection efficiency, and pCE2–5 and pCBHLHB1 are expression vectors. The values presented are luciferase activity (in relative luminescence units, RLU) divided by CAT activity (in cpm). Similar results were obtained in four independent transfection experiments. (B) NIH 3T3 cells were transfected in triplicate with the indicated vectors. The pG5B/CAT vector contains a minimal promoter and five concatamerized Gal4 DNA binding sites linked to a CAT reporter cassette. pSG4 is an expression vector that produces a full-length Gal4 protein. All samples were cotransfected with the Rous sarcoma virus-luciferase control vector to control for transfection efficiency; results are expressed as cpm/RLU. Similar results were obtained in two independent experiments. (C) Jurkat T cells were transfected in triplicate as described above for 7A with the indicated vectors. For these experiments, 2 μg of E(2,5)-luc, 2 μg of pCE2–5, and 8 μg of pCBHLHB1 were used. Similar results were obtained in three independent experiments.