Fig 1: Identification of the endothelin receptor as the novel target of SFX. a Schematic illustration of three acetylated SFX derivatives. N1, N1-acetylation site (blue). N4, N4-acetylation site (green). b The minimal inhibitory concentration (MIC) of SFX and its derivatives against Staphylococcus aureus ATCC 29213 and Escherichia coli ATCC 25922. c Measurement of the number of sEV and the amounts of sEV proteins. Left, the number of sEV. Right, the amounts of sEV proteins. n = 3. d Immunoblot (Top) and qRT-PCR analysis (bottom) of RAB27A in MDA-MB231 cells treated with 100 µM SFX or its structural derivatives. e Candidate proteins for binding to SFX by searching binding DB. Tanimato coefficients (Tcs) as the measure of similarity are summarized. f Detection of ETA by immunoblot. Eluted parts from the membrane fraction of MDA-MB231 cells were used for biotin-based pull-down assay. WT-SFX was used as a negative control. n = 3. g Immunoblot of various proteins in MDA-MB231 cells after transfection of different ETA siRNAs. AccuTargetTM siRNA was used for control siRNA. n = 3. h Immunoblot of Rab27a protein after transfection of each siRNA specific to AGTR1, CA13, or KMO into MDA-MB231. n = 3. i Dose response curve for the inhibition of binding of 125I-ET1 to the human ETA receptor. IC50, the half maximal inhibitory concentration. Ki the inhibitory constant, nH Hill coefficient. j Immunoblot of ETA and its ligand, ET1 and ET2 in MCF10A, MCF7, and MDA-MB231 cells. n = 3 per cell line. Experiments were performed with 95% confluent cells. Significance was determined using an unpaired two-tailed Student’s t-test. ***p < 0.001, **p < 0.005 and *p < 0.05. Error bar, SD. Source data (b–d, i–j) are provided as a Source Data file