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. 2012 Oct;92(4):753–764. doi: 10.1189/jlb.0412214

Figure 2. Intracellular signaling pathways activated by IL-4 and IL-13.

Figure 2.

IL-4 and IL-13 induce the tyrosine phosphorylation of STAT6. Activation of the type I receptor by IL-4 and the type II by IL-4 or IL-13 will induce the tyrosine phosphorylation of IRS2 with different efficiencies. The Grb2 site is restricted to the type I receptor. Activation of pathways downstream of IRS2, especially the PI3K pathway, have been shown to be critical for the STAT6-dependent transcription of arginase-1 and FIZZ1. Activation of STAT6-dependent genes is dependent on the recruitment of CREB-binding protein/p300 to the transcriptional complex. The mechanism by which the PI3K pathway modulates transcription of these genes is unclear.