Phosphorylated GSK3β (Ser9) is an inactivated modified form of Glycogen Synthase Kinase 3β, belonging to the serine/threonine kinase family and widely existing in human cells. It coregulates glucose metabolism, cell apoptosis, inflammatory response, tumorigenesis and neural development. Phosphorylation modification at the Ser9 site of GSK3β inhibits its kinase activity, blocks downstream pro-apoptotic, pro-inflammatory and metabolism-inhibiting signaling pathways, and maintains cellular physiological homeostasis. Abnormally decreased phosphorylation level at this site leads to sustained GSK3β activation, causing glucose metabolism disorder, nerve cell apoptosis and excessive inflammation, and promoting tumor proliferation, metastasis, Alzheimer's disease and metabolic disease progression. Excessively increased phosphorylation causes abnormal cell proliferation.