Targeted disruption of the Stat1 gene in mice reveals unexpected physiologic specificity in the JAK-STAT signaling pathway

The janus kinase (JAK)/signal transducers and activators of transcription (STAT) signaling pathway has been shown to be involved in many biological processes. JAK proteins are bound to cytokine receptors and signaling is triggered when cytokine binding induces receptor dimerization whereas STAT proteins are activated by tyrosine phosphorylation to form homodimers and heterodimers that activate cytokine-inducible genes. However, there is no information regarding the mechanism by which pathway specificity is manifested. An experiment on mice deficient in STAT1 is discussed to elucidate this mechanism.