This focus area is concerned with the study at the molecular and cellular level of the mechanisms whereby extracellular signals are converted into cellular responses. Specific areas of research include the mechanism and function of various intracellular signaling molecules and transcription factors; the study of post- transcriptional regulation of gene expression including RNA processing, RNA transport and protein translation; and DNA replication and cell cycle regulation. These issues are addressed in various physiological contexts including development, cardiovascular disease, vision, and viral and bacterial pathogenesis, utilizing a variety of different experimental paradigms ranging from in vitro cell culture and biochemical approaches to in vivo animal models.