FIG. 11.

In vitro binding of Spi-1/PU.1 to EBSs of the −270/−41 Fli-1 region. Radiolabeled oligonucleotides spanning the 5′ EBS (A and B) or 3′ EBS (C) of the −270/−41 Fli-1 region (Fig. 8), or radiolabeled oligonucleotide E74 containing a consensus EBS (D), were tested in EMSA using nuclear extracts prepared from 745-A cells treated or not with 5 mM HMBA as indicated. The presence (+) and/or absence (−) of the indicated specific or nonimmune serum or excess of unlabeled oligonucleotides (competitors) is indicated. Major observed complexes C1 to C3 (in panel A) or C (in panel C) are indicated by arrows. The identified Spi-1/PU.1 and Fli-1 complexes are marked. In panel D, two different preparations of 745-A cell extracts were used in EMSAs shown in lanes 1 to 3 and 4 to 9. Free probe is not visible in panel D. The sequences of the different oligonucleotides used either as probes or as competitors are given in Fig. 8 and in Materials and Methods.