Fig. 1

a Schematic representation of the structural domains of STAT proteins, adapted from (Liu et al. 2002). The STAT protein contains an N-terminal domain (ND) responsible for stabilizing the binding of STAT dimers to DNA. The “coiled-coil” domain (CCD) is involved in interactions with other proteins. The DNA binding domain (DBD) allows physical contact with the STAT response elements in the promoter of target genes. The linker domain connects the DBD to the “Src homology 2” domain (SH2) and is important in the dimerization of STAT proteins. A tyrosine residue (Y) in the TAD domain is phosphorylated and interacts with the SH2 domain of another monomer. The C-terminal TAD area is responsible for the transcriptional activation of target genes. Areas in purple represent the different sites of action of specific inhibitors of STAT3 that have been recently identified. b Schematic representation of the structural domains of JAK proteins, adapted from Braunstein et al. (2003). The N-terminal region of the JAK protein contains the JH3–JH7 domains (shown in purple) that are involved in protein binding with the receptor. Next, the JH2 domain (shown in blue) corresponds to the domain pseudokinase necessary to regulate the catalytic activity of JH1. The JH1 domain is found in the C-terminal and contains the kinase activity. This domain contains two tyrosines that play an important role in protein kinase activity