XPO1 and breast cancer: Interestingly, when MCF-7 breast cancer cells were treated with leptomycin B 39, 40 (LMB; the first specific inhibitor of CRM1, also known as elactocin, mantuamycin, and NSC 364372, a polyketide isolated from Streptomyces) under combined treatment with TNF-α and Orp to inhibit β-catenin, Orp could not inhibit the expression of β-catenin.