FIG. 5.

DNA binding activity of recombinant Fli-1 and Spi-1/PU.1 proteins to the Rb promoter. Lysates of bacterial cells (1, 3, or 5 μl) expressing GST–Fli-1, GST–Spi-1/PU.1, or GST were incubated with the ³²P-labeled Rb oligonucleotides. Binding reactions were performed in the presence of the nonspecific competitor poly(dI-dC) and the presence (+) or absence (−) of cold specific Rb competitor DNA. Complexes were resolved on a 5% polyacrylamide gel. As a control, binding with no protein (None) was performed.