CD4 T(h) are critical for orchestrating adaptive immune responses. The 
expression of the transcription factor GATA3 (GATA-binding protein 3) is 
up-regulated or down-regulated during T(h)2 or T(h)1 cell differentiation, 
respectively. Furthermore, GATA3 is responsible for induction of T(h)2 
differentiation and represses T(h)1 differentiation. In this review, we present 
an updated view on the molecular mechanisms through which GATA3 regulates 
T(h)1/T(h)2 differentiation. During T(h)2 cell differentiation, GATA3 directly 
binds to the T(h)2 cytokine gene locus at several regions and regulates 
expression. On the other hand, GATA3 inhibits T(h)1 cell differentiation by 
preventing up-regulation of IL-12 receptor β2 and STAT4 (signal transducer and 
activator of transcription 4) and neutralization of Runx3 (runt-related 
transcription factor 3) function through protein-protein interaction. GATA3 may 
also directly act on the Ifng gene. In summary, GATA3 serves as a 
transcriptional activator or repressor through direct action on transcriptional 
machinery and/or affecting chromatin remodeling at many critical loci encoding 
cytokines, cytokine receptors, signaling molecules as well as transcription 
factors that are involved in the regulation of T(h)1 and T(h)2 differentiation.