FIG. 3.

DNA binding of uninfected and infected cell Sp1. Electrophoretic mobility shift assay using KOS-infected Vero cell lysates. Cell lysates were prepared from uninfected and infected cells at the indicated times p.i. The cell lysate was incubated with a ³²P-labeled oligonucleotide containing an Sp1 binding site in the presence of nonspecific competitor poly(dI-dC). For supershifts, Sp1 antibody was added where indicated as described in Materials and Methods. Purified baculovirus-produced Sp1 was used as a control. The bands were resolved on a nondenaturing 5% polyacrylamide gel. The complexes labeled a, b, and c are described in the text.