IPO8 (importin 8) is a nuclear transport receptor mediating cytoplasm-to-nucleus protein import through a Ran-GTP-dependent mechanism at the nuclear pore complex. As an autonomous receptor or adapter protein, IPO8 recognizes nuclear localization signals (NLS) and facilitates translocation of diverse cargo proteins including SRP19, Argonaute-microRNA complexes, JUN, NF-κB p65, EIF4E, and SMAD transcription factors [UniProt function]. The directional specificity of nuclear import is conferred by asymmetric cytoplasmic-to-nuclear distribution of Ran-GTP/GDP forms, with Ran-GTP binding at the nuclear side triggering cargo release and importin recycling 1. IPO8 demonstrates stable expression across diverse cell types and tissues, serving as a reliable reference gene for RT-qPCR normalization in adipose tissue 2, cancer cell lines 3, and multiple tissue contexts 4. Transcriptionally, RUNX2 controls IPO8 basal expression in osteoblasts through binding to a conserved promoter motif (-496 to -501 bp), with synchronized expression during osteoblast differentiation 5. Clinically, bi-allelic IPO8 loss-of-function mutations cause early-onset thoracic aortic aneurysm with connective tissue manifestations including arachnodactyly, joint hypermobility, and facial dysmorphisms resembling Loeys-Dietz syndrome 6. Additionally, elevated IPO8 expression in periodontitis tissues correlates with disease severity and macrophage infiltration, with IPO8 knockdown reducing NF-κB-mediated inflammatory responses 7, indicating IPO8's role in inflammation regulation.