Cell signaling provides two important aspects of complex cellular functions: intercellular communication (such as transmitter secretion); coordination of intracellular events (such as protein biosynthesis). Electrical and biochemical signals provide the means for both coordinating bodily functions and responding to changes in a cell’s microenvironment. Breakdown in cell signaling often leads to abnormalities such as cancer, heart disease, diabetes, and neurological disorders. Understanding mechanisms of cell signaling will provide us with the critical information required to develop targeted treatments for these types of diseases. Cell signaling is studied using a wide variety of techniques including pharmacology, biochemistry, biophysics, molecular biology, and proteomics.