Fig. 3.

Effects of HIV-1 Tat on binding of SMAD proteins to the JCV CR as determined by ChIP. KG-1 cells were transfected to express SMAD2 and -3, SMAD4 or Fast1 in the presence or absence of added exogenous Tat at 10⁻¹² M. ChIP was performed using antibodies against SMAD2/3, SMAD4 or Fast1 as described in Methods. The results of ChIP are presented as acrylamide gel bands of a PCR segment amplified from the immunoprecipitate using primers from the JCV CR. T, Transfected cells; Unt, untransfected cells; T+Tat, transfection in the presence of exogenous Tat. L, B and G1 are negative controls representing no immunoprecipitation, precipitation with protein G agarose beads alone, and beads with an irrelevant IgG1, respectively.