SATB1 and CBP. (A) Proteins were isolated from K562 nuclear extract using anti-SATB1 antibody (α-SATB), anti-CBP (α-CBP), or preimmune serum (α). Western blotting with anti-SATB1 antibody and anti-CBP antibody indicates coimmunoprecipitation of SATB1 family protein (SATB) with CBP. The nuclear extract from K562 cells was used as a positive control. (B-F) Luciferase activity was determined in reporter gene assays in K562 (B-C) and HeLa (E-F) cells using pREP4/ϵ (ϵ) and cotransfection with expression vectors for SATB1 (SATB; ▪), E1A, and a mutant E1A (mut; B,E), and increasing amounts of CBP expression vector (C-D,F) as indicated. C_o indicates the promoterless pREP4/Luc control. (G) Endogenous ϵ- and γ-globin gene mRNA expression was determined for K562 cells with and without overexpression of SATB1, E1A, or mutant E1A as indicated. Globin gene expression is normalized β-actin. Error bars represent SD from 3 independent experiments.