Binding and activation of STAT3 toDNMT1gene promoter/enhancer region in vivo. Cell lysates from T-cell lymphoma cell lines 2A and 2B were examined in the chromatin immunoprecipitation (ChIP) assay before (input) and after immunoprecipitation using anti-STAT3 antibody with an unrelated (ALK) antibody serving as the negative control. DNA binding was detected in the ChIP assay using PCR primer pairs corresponding to promoter 1 (A, P1) and enhancer 1 (B, E1) regions. Binding to the 3′-end of the DNMT1 gene served as an additional negative control. (C) STAT3 effect on activity of the DNMT1 promoter and enhancer. SUDHL-1 cells that constitutively expressed activated STAT3 were transfected with firefly luciferase constructs containing promoter 1 and enhancer 1 of the DNMT1 gene in either wild-type form (P1 and E1, respectively) or with mutated (M) TT and AA pairs that were substituted with the CC pairs. Results are presented in relative luciferase unit (RLU) after normalization based on expression of the cotransfected renilla luciferase gene.