A kinase is an enzyme that plays a crucial role in cellular processes by transferring phosphate groups from high-energy molecules, like ATP, to specific substrates, typically proteins. This process, known as phosphorylation, can activate or deactivate the target proteins, thereby influencing various cellular functions such as metabolism, cell division, and signal transduction. Kinases are essential in regulating many biological pathways and are involved in numerous diseases, including cancer. There are different types of kinases, such as protein kinases and lipid kinases, each targeting specific molecules. Their activity is tightly regulated to maintain cellular homeostasis and proper function.