Regulation of the activity of Ci deletion mutants by Cos2. (A) A summary of UAS-Ci constructs analyzed by in vivo coexpression assay. Filled boxes indicate the Zn-finger DNA-binding domain (from aa 440 to aa 620), and open boxes indicate dCBP bind domain (CBP) or the Gal4 activation domain (AD). Numbers indicate the positions of amino acid residues where Ci deletion mutants end. Two copies of HA tag (not shown) are fused at the N terminus of each construct to allow monitoring the expression level. (B, B′, C, C′) Wing discs expressing MS1096/UAS-CiΔN2 (B) or MS1096/UAS-CiΔNC1 (C) show ectopic ptc-lacZ expression uniformly in the wing-pouch region. However, the ectopic ptc-lacZ expression is suppressed by coexpressing UAS-Cos2 (B′ and C′). (D, D′,E, E′) Wing discs expressing MS1096/UAS-CiGA1 (D) or MS1096/UAS-CiGA2 (E) show ectopic ptc-lacZ expression with higher levels in P compartment cells than in A compartment cells. The ectopic ptc-lacZ expression induced by CiGA1 and CiGA2 persists when UAS-Cos2 is coexpressed (D, E′).