STATs are proteins that play a crucial role in cell signaling. They help transmit information from outside the cell to the nucleus, influencing how cells respond to various stimuli, such as hormones and growth factors. When activated, STATs can enter the nucleus and regulate the expression of specific genes, impacting processes like cell growth, differentiation, and immune responses. There are several types of STATs, including STAT1, STAT2, STAT3, and STAT5, each with unique functions. Dysregulation of STATs has been linked to various diseases, including cancer and autoimmune disorders, making them important targets for research and potential therapies.