Exogenous CIITA promoter activity in various T-cell lines. pGL3-CIITA-PIII (PIII) or pGL3-CIITA-PIV (PIV) were transiently transfected in CIITA-deficient Jurkat, Molt-4, CEM, and HSB-2 T-ALL cells and the CIITA-expressing HH, H9, Karpas-299, and HUT78 T-lymphoma cell lines. Promoter activity was determined 48 hours after transfection; pGL3-basic (C), which lacks a promoter preceding the luciferase gene, is used as background control. Promoter activity is measured as relative luciferase units (RLUs) and corrected for transfection efficiency using a β-actin Renilla construct. Error bars represent SD.