ACTR3 (actin related protein 3) is an ATP-binding component of the Arp2/3 complex that mediates actin polymerization and branched actin network formation 1. The protein plays essential roles in cellular motility by providing the force for cell movement through cytoplasmic actin reorganization 1. ACTR3 functions through ACTR2/ARP2-ACTR3/ARP3-dependent actin remodeling mechanisms, as demonstrated in lysosomal trafficking where it promotes exocytosis of damaged lysosomes 2. In oocyte meiosis, ACTR2 (closely related to ACTR3) is crucial for spindle assembly and migration through autophagy regulation 3. ACTR3 also contributes to cellular differentiation processes, with PYK2-mediated mechanotransduction triggering F-actin polymerization and ACTR3 nuclear translocation during monocyte-to-macrophage differentiation 4. In microvascular biology, endothelial-induced ACTR3 upregulation triggers pericyte morphological adaptation 5. Clinical relevance includes its identification as a prognostic biomarker in cervical cancer, where high ACTR3 expression correlates with poor outcomes and affects tumor immune microenvironment 6. Additionally, ACTR3 has been implicated in non-small cell lung cancer progression through the FXR1-IL-35 axis pathway 7, and its methylation patterns are altered in autism spectrum disorder 8.