Cyclic GMP, or cGMP, is a molecule that plays a crucial role in cellular signaling. It is produced from GTP (guanosine triphosphate) by the enzyme guanylate cyclase. cGMP acts as a second messenger, helping to transmit signals from hormones and neurotransmitters to various cellular processes, including relaxation of smooth muscle and regulation of blood flow. In addition to its role in smooth muscle relaxation, cGMP is involved in other important functions, such as vision and neurotransmission. It helps modulate the activity of certain proteins and enzymes, influencing processes like cell growth and apoptosis. Overall, cGMP is essential for maintaining various physiological functions in the body.