FIG. 2.

Sp1 interacts with HDAC1 in vivo. Whole-cell extracts were immunoprecipitated with anti-Sp1 antibody (Pep2), an irrelevant control antibody (anti-HA), anti-Rb antibody (C-15), anti-Sin3A antibody (AK-11), and anti-Sin3B antibody (AK-12). (A) Sp1 associates with HDAC activity in resting Swiss 3T3 cells similarly to the known HDAC1-binding proteins Rb, Sin3A, and Sin3B. HDAC activity was measured as described previously (5). (B) HDAC1 coimmunoprecipitates with Sp1. HDAC1 was detected by Western blot analysis with the anti-HDAC1 antibody.