The E-box motifs of CIITA-PIII confer high promoter activity in B cells. (A) Schematic illustration of CIITA-PIII reporter plasmids used in transient transfection assays with Ramos B cells (B), U937 monocytic cells (C), and Jurkat cells (D). Ramos and Jurkat cells were harvested after 48 hours, monocytic cells were harvested after 24 hours, and the cells were analyzed for luciferase activity. Luciferase activity values were normalized with Renilla luciferase activity values, represent the means of 3 experiments, and were related to the activity of PIIIfl. Error bars indicate SEM.