CHMP4A (charged multivesicular body protein 4A) is a core component of the endosomal sorting complex required for transport III (ESCRT-III), which mediates essential membrane fission events including multivesicular body formation, cytokinesis, and viral budding 1. The protein functions in topologically equivalent membrane remodeling processes, with ESCRT-III proteins mediating vesicle extrusion and membrane fission activities 2. CHMP4A demonstrates selectivity in viral interactions, being specifically required for flavivirus assembly but not replication, through recruitment by viral NS3 protein late domain motifs 3. In cancer biology, CHMP4A exhibits dual roles: it acts as a tumor suppressor in breast cancer by promoting CD8+ T-lymphocyte infiltration via the LSD1/IFNβ axis 4, while functioning as an oncogene in hepatocellular carcinoma where it promotes tumor progression and modulates immune checkpoints including TIM3/LGALS9 5. The protein also influences pyroptosis, a programmed cell death pathway important in immune responses, with reduced CHMP4A expression associated with decreased immune cell infiltration in melanoma 6. Genetic variants in CHMP4A correlate with survival outcomes in head and neck cancers, likely through effects on gene expression 7.