STAT1 is a protein that plays a crucial role in the immune system and cellular signaling. It is part of the STAT (Signal Transducer and Activator of Transcription) family, which helps transmit signals from outside the cell to the nucleus, influencing gene expression. STAT1 is primarily activated by cytokines, such as interferons, which are important for fighting infections and regulating immune responses. When STAT1 is activated, it forms dimers and translocates to the cell nucleus, where it binds to specific DNA sequences to regulate the expression of target genes. This process is essential for the development of immune responses and can also be involved in various diseases, including cancer and autoimmune disorders.