Figure 3.

PIAS1 inhibits the DNA binding activity of Stat1. EMSA analysis was performed with nuclear extracts prepared from Daudi cells with (+) or without (−) IFN-α treatment in the absence or presence of GST, GST–PIASxα, GST–PIAS3, or GST–PIAS1 proteins (15–75 ng) as indicated. The probe used is a high-affinity Stat1–DNA binding site (10). The concentrations of GST fusion proteins were estimated on 7% SDS/PAGE with various dilutions of BSA as the standard.