Physiological significance of STAT proteins: investigations through gene disruption in vivo

Signal transducers and activators of transcription (STATs) were discovered as mediators of type I interferon-induced gene expression. This family of t ranscription factors has been found in widespread signaling pathways, espec ially those involving cytokines-regulating the immune response. Because a p lethora and often confusing set of activators for STAT proteins was observe d in cell culture models, it became important to define the physiologically relevant actions of these molecules. One approach to this question has bee n through the targeted disruption of STAT genes in transgenic mice. Now tha t all seven STAT genes have been disrupted, both the high degree of STAT se lectivity as well as many surprising and unexpected complexities are beginn ing to be characterized.