Signal transduction is the process by which cells receive and respond to signals from their environment. It involves a complex and highly regulated series of molecular interactions that transmit information from the cell surface to the nucleus, where gene expression can be altered. This process is critical for many physiological functions, including cell growth, differentiation, metabolism, and immune responses. Researchers in fields such as pharmacology, biochemistry, and molecular biology study signal transduction to understand how cells function and develop new therapies for diseases that involve signaling dysregulation.