CBS9106 directly binds to CRM1 in a competitive manner with LMB. (A) MM.1S and RPMI-8226 cells were treated with vehicle or CBS9106 (50 or 200nM) in the presence or absence of LMB (2nM) for 8 hours. The whole-cell lysates were analyzed by immunoblotting for CRM1 and actin. (B) RPMI-8226 cells were treated with biotinylated compounds, including biotin (100nM), S08776B-biotin (100nM), CBS9106-biotin (100nM), or LMB-biotin (1nM) for 1 hour in the presence or absence of pretreatment with LMB (10nM) or CBS9106 (1μM) for 1 hour. The whole-cell lysates were subjected to pull-down analysis with the use of streptavidin beads. Captured proteins were analyzed by immunoblotting. (C) The structures of biotinylated compounds CBS9106 (top) and S08776B, an inactive analog of CBS9106 (bottom).