IPO13 (importin 13) is a bidirectional nuclear transport receptor mediating Ran-dependent nucleocytoplasmic shuttling of diverse cargo substrates 1. As a member of the importin-β family, IPO13 functions by docking importin/substrate complexes to the nuclear pore complex and facilitating translocation through an energy-dependent mechanism, with cargo release triggered by Ran-GTP binding at the nucleoplasm 2. IPO13 imports multiple functionally distinct cargoes including the glucocorticoid receptor, ALYREF, SIRT6, and c-Jun 2345. Notably, IPO13 retains transport capacity under stress conditions when other importins are impaired, selectively importing pro-apoptotic nuclear clusterin while failing to export KU70, thereby regulating stress-induced cell death 1. IPO13 is highly expressed in corneal epithelial progenitor cells where it maintains their proliferative phenotype 6. Disease relevance includes pterygium pathogenesis through K17 and c-Jun regulation 5, diabetic vascular complications via SIRT6-mediated glycolysis reprogramming 4, paclitaxel resistance in triple-negative breast cancer via ALYREF nuclear trafficking 3, and developmental eye defects including ocular coloboma and microphthalmia 7. IPO13 mutations cause autosomal recessive ocular coloboma with microphthalmia and cataract, demonstrating essential roles in eye morphogenesis 7.