Naïve CD4+CD62L+ T cells were isolated from WT or Stat4−/− C57BL/6 mice and cultured under Th1 polarizing conditions. On day 5, cells were harvested, stimulated with IL-12 for the indicated time points, and gene expression was examined by qRT-PCR (A, C) or used for STAT4 binding, chromatin modifying enzymes and histone modification analyses by ChIP assay using qPCR primers specific for the promoters of the indicated genes (B, D). Data are average of replicate samples ± S.D. and representative of three independent experiments with similar results. Gene names are indicated adjacent to the corresponding line (A, B) representing mRNA expression or ChIP results at the promoter.