FIG. 5.
CBP relieves the inhibition of collagen α2(I) promoter activities by CIITA. (A) Increasing amounts of CBP were cotransfected with CIITA and/or carrier DNA, as depicted in the figure. The influence of CBP on CIITA-mediated suppression of the collagen promoter was measured by comparing the collagen luciferase reporter gene activity in the absence (lane 3) or presence (lane 4 to 6) of CBP. The quantity of CBP used to transfect the cells are depicted in the figure. These experiments were repeated three times. (B) COS7 cells (9 × 105) were cotransfected with 3 μg of FlagCIITA and various amounts of CBP (1.5, 3.0, and 4.5 μg for lanes 2, 3, and 4, respectively) or its empty control vector, CMV5 (lane 1). CMV5 empty vector was also added to lanes 1 to 3 such that the total amount of plasmid transfected is the same in all of the samples. Cells were lysed with 1.5 ml of RIPA buffer 36 h after transfection, and 25 μl of the samples was subjected to SDS–10% polyacrylamide gel electrophoresis resolution. The expression of Flag CIITA was analyzed by immunoblotting (IB) using anti-Flag antibody.