STAT5B is a protein that plays a crucial role in cell signaling, particularly in response to various hormones and growth factors. It is part of the STAT (Signal Transducer and Activator of Transcription) family, which helps transmit signals from the cell surface to the nucleus, influencing gene expression and cellular functions. This protein is essential for processes such as cell growth, survival, and differentiation. Abnormalities in STAT5B can be linked to various diseases, including certain types of cancer and immune disorders, highlighting its importance in maintaining normal cellular activities and overall health.