ARF4 is a GTP-binding protein that functions as a critical regulator of intracellular protein trafficking through multiple cellular pathways. Structurally, ARF4 localizes to distinct nanodomains on the cis-Golgi and ER-Golgi intermediate compartments (ERGIC), where it defines specialized membrane regions decorated with COPI coat proteins and segregated from ARF1-containing domains 1. Mechanistically, ARF4 serves dual roles: it regulates retrograde trafficking between the ER and Golgi apparatus and forms a functional ciliary-targeting complex with Rab11, ASAP1, Rabin8, and RAB11FIP3 that directs sensory receptor trafficking to primary cilia 2. During viral infection, ARF4 activation is exploited by pathogenic RNA viruses (ZIKV, IAV, SARS-CoV-2) to facilitate Golgi translocation and release of viral progeny; ARF4 depletion redirects viruses for lysosomal degradation, and ARF4-targeting peptides show therapeutic efficacy in mice 3. In disease contexts, ARF4 activity is regulated by 25-hydroxycholesterol binding, which protects against diabetic kidney disease by maintaining endothelial cell survival through interference with ASAP1-mediated ARF4 inactivation 4. Additionally, ARF4-mediated retrograde trafficking drives glioblastoma chemoresistance by promoting nuclear EGFR trafficking and downstream DNA repair signaling; ARF4 suppression significantly enhances temozolomide sensitivity in patient-derived xenografts 5. These findings establish ARF4 as a multifunctional trafficking regulator with therapeutic potential as an antiviral and chemosensitizing target.