Carries out a dual function: signal transduction and activation of transcription. Involved in IL4/interleukin-4- and IL3/interleukin-3-mediated signaling. {ECO:0000269|PubMed:17210636, ECO:0000269|PubMed:36758835, ECO:0000269|PubMed:36884218}. This is the function of STAT6 (signal transducer and activator of transcription 6, ENSG00000166888).