P2Y12 also known as P2RY12 is a member of the family of G-protein coupled receptors. P2Y12 is a Gi-coupled GPCR that senses extracellular ADP to suppress cAMP signaling and coordinate platelet activation, aggregation, and thrombus stabilization through downstream PI3K/AKT and integrin signaling. Beyond hemostasis, P2Y12 is a characteristic marker of homeostatic microglia and modulates chemotaxis, process motility, and neuroimmune surveillance in response to nucleotides. Altered P2RY12 activity or expression has been linked to abnormal platelet reactivity and to microglial state changes observed in neuroinflammatory and neurodegenerative contexts.