Chromosome maintenance protein 1 (CRM1) is a nuclear export receptor involved in the active transport of tumor suppressors (eg, p53 and nucleophosmin) whose function is altered in cancer because of increased expression and overactive transport. Blocking CRM1-mediated nuclear export of such proteins is a novel therapeutic strategy to restore tumor suppressor function. Orally bioavailable selective inhibitors of nuclear export (SINE) that irreversibly bind to CRM1 and block the function of this protein have been recently developed. CRM1 is the sole exporter of many tumor-suppressor proteins (TSPs), and functions as a proto-oncogene by transporting these tumor suppressors from the nucleus, where they are active, to the cytoplasm, where their activity is abrogated.