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Importazole is a cell-permeable inhibitor of importin-β, which transports cargo molecules bearing a nuclear localization signal into the nucleus. Importazole prevents nuclear import of GFP-tagged nuclear factor of activated T cells (NFAT-GFP) in HEK293 cells (IC₅₀ = 15 μM), which is reversible upon importazole washout. Importazole does not interfere with transportin-mediated nuclear import or chromosomal maintenance 1 (CRM1)-mediated nuclear export. Importazole inhibits nuclear import of topoisomerase IIβ binding protein 1 (TopBP1) in Xenopus egg extracts and of NF-κB in multiple myeloma cells. It also induces defects in spindle and microtubule formation in vitro.

Importazole is an importin-β inhibitor.

ChEBI: N-(1-phenylethyl)-2-(1-pyrrolidinyl)-4-quinazolinamine is a member of quinazolines.

Importazole is an inhibitor of importin-β transport receptors. During interphase, the transport receptor importin-β carries cargoes into the nucleus, where RanGTP releases them. Importazole somehow disrupts the importin/RAN interaction. Importazole is selective among other transporters. Compounds are imported into, but not out of, cells.

1) Soderholm et al. (2011), Importazole, a small molecule inhibitor of the transport receptor importin-β; ACS Chem. Biol., 6 700 2) Bird et al. (2013), RanGTP and CLASP1 cooperate to position the mitotic spindle; Mol. Biol. Cell, 24 2506 3) Bai et al. (2014), Importin β-dependent nuclear import of TopBP1 in ATR-Chk1 checkpoint in Xenopus egg extracts; Cell Signal., 26 857 4) Yan et al. (2015), Importin β1 mediates nuclear factor-κB signal transduction into the nuclei of myeloma cells and affects their proliferation and apoptosis; Cell Signal., 27 851 5) Zhu et al. (2018), KPNB1 inhibition disrupts proteostasis and triggers unfolded protein response-mediated apoptosis in glioblastoma cells; Oncogene 37 2936