EEA1 (Early Endosome Antigen 1) is a landmark scaffold protein for intracellular vesicle trafficking, encoded by the EEA1 gene with a molecular weight of approximately 162 kDa, and serves as a specific biomarker of early endosomes. Ubiquitously expressed in eukaryotic cells and localized on early endosome membranes, EEA1 binds to Rab5 and phosphatidylinositol to mediate early endosome formation, fusion and substance sorting, regulating endocytic trafficking, receptor recycling, intracellular signal transduction and vesicle homeostasis. As a core component of the cellular endocytic and vesicle transport system, abnormal EEA1 expression disrupts intracellular material transport and signal transduction, impairs cell proliferation, metabolism and stress responses, and is closely correlated with tumor invasion, inflammatory injury and organelle dysfunction.