Fig. 1. The canonical model of JAK/STAT signalling. Pre-dimerised complexes of a pathway receptor (grey) and JAKs (blue) are activated following ligand (red) binding. Phosphorylation (purple circles) of the JAKs and the receptors generate docking sites for the normally cytosolic STATs that are recruited to the active complex. Following phosphorylation of the STATs, STAT dimers form, which translocate to the nucleus and bind to a palindromic DNA sequence in the promoters of target genes to activate their transcription. The names of the pathway components in Drosophila are provided in brackets in the key.