STAT3 and cancer: To evaluate the specific apoptotic effect of LA in STAT3-dependent or independent cancer cells, a cytotoxicity assay was conducted in breast cancer (MDA-MB-453; STAT3 mutant, MCF-7; STAT3 wild type) and prostate cancer (PC-3; STAT3 null, DU145; STAT3 wild type) cell lines by 3-(4,5-dimethylthiazol-2-yl)-2,5diphenyltetrazolium bromide (MTT) assay.