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. Author manuscript; available in PMC: 2014 Mar 1.
Published in final edited form as: Immunol Rev. 2013 Mar;252(1):12–23. doi: 10.1111/imr.12032

Fig. 3. Early Th2 fate decision regulated by strength of TCR signals.

Fig. 3

When naive 5C.C7 CD4+ T cells receive strong TCR signals, strong and prolonged ERK activation is induced. This intense ERK activation results in failure to produce early IL-4 by suppressing IL-4-independent TCR-driven early GATA-3 expression and by transiently blocking IL-2R-mediated STAT5 activation (Right). By contrast, when naive 5C.C7 CD4+ T cells receive weak TCR signals, the level of ERK activation is not so strong as to suppress early GATA-3 expression or to inhibit the IL-2/STAT5 pathway. GATA-3 and STAT5 subsequently translocate into the nucleus and bind to the DNase hypersensitivity sites II/III and V in the Il4 gene locus, leading to the induction of early IL-4 production, completion of the induction phase and subsequent Th2 polarization process (Left).