['T-bet is crucially implicated in Th1 differentiation due to its strong promoting activity for IFN-gamma gene transcription. However, the regulatory role of T-bet in Th2 cytokines is not fully delineated.', 'The effect of T-bet on mRNA expression as well as the promoter activity of IL-4 in human T cells was investigated by employing quantitative RT-PCR and fluorescence-based promoter reporter assay procedures.', "IL-4 mRNA expression as well as the transcriptional activity of 5'-flanking region in the IL-4 gene encompassing -1105 to +4 in Jurkat cells was clearly upregulated upon stimulation. The inducible mRNA expression and the promoter activity of IL-4 were significantly diminished by ectopic expression of T-bet."] Is iL-4 gene transcription in human T cells suppressed by T-bet?