The role of STATs in proliferation, differentiation, and apoptosis

The spectrum of biological systems which makes use of the signal transducer s and activators of transcription (STAT) paradigm extends beyond the interf eron system in which it was first discovered to include many other cytokine s and agonists. Having catalogued which STATs are activated by each stimulu s, investigators have turned their attention to defining the biological pro cesses and the genes regulated by the STAT pathway. These studies are in th eir early stages. Although many tools have been developed to probe the STAT pathway, e.g., mutant receptors, dominant-negative STATs, chemically dimer izable STATs, and mice lacking STAT proteins, more is known about the biolo gical phenomenon affected than the molecular mechanism or the STAT-regulate d genes involved. The cellular events currently believed to utilize STAT-de pendent pathways can be grouped according to those which affect cell growth , differentiation, and apoptosis.