Effects of inducible nitric oxide synthase (iNOS) inhibitors on tumor cell proliferation, migration, and mammosphere formation in triple-negative breast cancer (TNBC) cell lines. Proliferation (A, B) and primary (C) and (D) secondary mammosphere, and migration index of MDA-MB-231 and SUM159 cell lines treated with 1400 W (E) and L-NMMA (F) for 96 hours. Results were normalized to vehicle. Data are presented as mean ± standard error of the mean. *P <0.05, **P <0.01, ***P <0.001, ****P <0.0001. 1400 W, N-[[3-(aminomethyl)phenyl]methyl]-ethanimidamide; L-NMMA, NG-monomethyl-L-arginine; MSFE, mammosphere-forming efficiency.