The extract of Saussurea lappa root was prepared as previously described4. Briefly, 10 g of Saussurea lappa roots were crushed into powder, and then was extracted with 100 mL hexane by sonication. The filtrates were evaporated to get VOSL. Analytic results from comprehensive two-dimensional gas chromatography- time-of-flight mass spectrometry (LECO Corporation, St Joseph, MI, USA) indicated that Cos and Dehy are the main ingredients of VOSL, accounting for nearly 72% of VOSL by weight (Supplementary Fig. S2 and Table S4). Commercial pure Cos, Dehy, or test sample of VOSL were dissolved in dimethyl sulfoxide (DMSO) to 10 mg/mL as a stock solution. According to the previous results of MCF-7 cell proliferation assays, 10%, 30% and 50% maximal inhibitory concentrations (IC10, IC30 and IC50) of Cos were calculated to be 0.9, 1.3 and 2.2 μg/mL, respectively. IC10, IC30 and IC50 of Dehy were 0.7, 1.1 and 1.7 μg/mL, respectively. IC10, IC30 and IC50 of CD were 0.4, 0.9 and 1.4 μg/mL, respectively. IC10, IC30 and IC50 of VOSL were 1.5, 2.4 and 3.3 μg/mL, respectively4. Moreover, according to the previous results of MDA-MB-231 cell proliferation assays, 10%, 30% and 50% maximal inhibitory concentrations (IC10, IC30 and IC50) of Cos were calculated to be 1.1, 2.3 and 4.2 μg/mL, respectively. IC10, IC30 and IC50 of Dehy were 0.8, 1.5 and 3.3 μg/mL, respectively. IC10, IC30 and IC50 of CD were 0.7, 1.3 and 2.8 μg/mL, respectively. IC10, IC30 and IC50 of VOSL were 1.3, 2.8 and 4.6 μg/mL, respectively.