Disclosing JAK/STAT links to cell adhesion and cell polarity

The components of many signalling pathways are localised in specific cellular compartments in polarised cells. This is particularly clear in the case of the receptors that localise to the apical or basal membrane in the epithelial cells. In many cases this subcellular localisation is important for the activation of the signalling pathways. In this review we analyse recent developments uncovering an interesting interplay between JAK/STAT signalling and components regulating cell polarity and adhesion during development. Not only the JAK/STAT signalling components are polarised in epithelial cells but many genes controlling cell polarity and adhesion are targets of STAT and in some cases these components act as pathway activators. The fact that in most morphogenetic processes cell adhesion and polarity proteins are regulated downstream of the pathway, hints at a possible unifying mechanistic explanation for the diverse morphogenetic processes controlled by JAK/STAT during development.