Figure 4.

FN-induced SIE-binding activity. (A and C, left) SIE complex formation. Nuclear extracts were prepared from HUVECs plated for 40 min on FN- or LM-coated dishes (+) or kept in suspension (−). Thirty minutes before the addition of radiolabeled SIE oligonucleotides, the indicated extracts were treated with a 50-fold excess of unlabeled oligonucleotide (Competitor). The DNA–protein complexes were then resolved by nondenaturing PAGE. (B and C, right) FN- or LM-induced SIE-binding complex is antigenically related to STAT5A. Nuclear extracts from HUVECs plated on FN or LM were incubated for 1 h at 4°C with an anti-STAT5A or an anti-STAT5B antiserum as indi-cated before adding a radiolabeled SIE oligonucleotide probe. DNA–protein complexes were resolved on a nondenaturing polyacrylamide gel. The SIE complexes (lower) and the supershifted species (upper) are indicated by the arrows.