Janus kinase (JAK)

Janus kinases (JAKs) are a family of enzymes inside cells that transmit signals from certain hormones and immune system proteins called cytokines. When these molecules bind to receptors on a cell's surface, JAKs activate a chain reaction inside the cell that helps regulate immune responses, blood cell production, and inflammation. They act as crucial messengers in cell communication, ensuring that the body responds appropriately to various signals. Because of their central role, JAKs are targets for drugs used to treat autoimmune diseases and blood disorders by modulating immune activity.