Phosphoinositide 3-kinase (PI3K) is an enzyme that plays a crucial role in cellular functions, including growth, proliferation, and survival. It is involved in signaling pathways that respond to various stimuli, such as hormones and growth factors. By converting a specific lipid in the cell membrane, PI3K generates signaling molecules that activate other proteins, leading to various cellular responses. PI3K is composed of different subunits, which can be categorized into three classes: Class I, Class II, and Class III. Each class has distinct functions and regulatory mechanisms. Dysregulation of PI3K signaling is associated with several diseases, including cancer, making it a target for therapeutic interventions.