Figure 2. Polypeptides bind to their associated receptors and trigger the tyrosine (Tyr) kinase (TK) events of the receptors, Src or JAKs. Underlying STAT-3 action is the stimulated receptor for phosphorylation on specific Tyr residue by TKs that causes STAT-3:STAT-3 dimerization and stimulation. STAT-3 mounts up in the nucleus, where it binds to specific DNA response elements in the promoters of target genes, which causes gene transcription.
