The CIITA N-term 1-252, but not the C-term 253-1130, region inhibits Tax-2 transactivating activity in 293T cells. A)- Luciferase gene reporter assay performed in 293T cells transiently co-transfected with fixed amounts (0.2 μg) of pLTR-II-Luc and pcTax-2 V5.(0.05 μg) vectors and in the absence or presence of increasing amounts (0.5-1 μg) of vectors coding for Flag-tagged CIITA wt (pfCIITA 1-1130) and fragments (pfCIITA 1-252 and pfCIITA 253-1130). Lower amounts of vector coding for flagCIITA 1-321 fragment (0.25-0.5 μg) were transfected. The black histogram represents the LTR-2 promoter activation by Tax-2 (bar 3). Bar 1 represents the control activity of the pcDNA3 vector alone. B)- CIITA did not affect basal promoter activity even after transfection of increasing amounts of CIITA plasmid. The expression of recombinant fCIITA proteins in all cell extracts were detected by anti-Flag Western blot (WB) (bottom panel).