STAT3 is a protein that plays a crucial role in cell signaling, particularly in response to various growth factors and cytokines. It is part of the Signal Transducer and Activator of Transcription family and helps regulate important cellular processes such as growth, survival, and differentiation. When activated, STAT3 moves into the cell nucleus to influence gene expression. Abnormal activation of STAT3 is often associated with various diseases, including cancer and autoimmune disorders. In many tumors, STAT3 promotes cancer cell proliferation and survival, making it a target for potential therapeutic interventions. Understanding STAT3 is essential for developing treatments that can inhibit its harmful effects in disease contexts.