SC-1 and SC-43 demonstrate more potent apoptosis and p-STAT3 inhibition than sorafenib in breast cancer cells. A, dose-escalation effects of sorafenib, SC-1 and SC-43 on apoptosis in six breast cancer cell lines. Cells were exposed to sorafenib, SC-1 or SC-43 at the indicated doses for 36 hours. Apoptotic cells were analyzed by flow cytometry. Points, mean; bars, SD (n = 3). *P <0.05 compared to sorafenib treatment at each indicated dose. B, dose-dependent analysis of p-STAT3 and STAT3 in drug treated breast cancer cells. Cells were exposed to sorafenib, SC-1 or SC-43 at the indicated doses for 36 hours. Cell lysates were prepared and assayed for these molecules by western blotting. Western blot data are representative of three independent experiments. The ratio of p-STAT3 to STAT3 is shown below each western blot data set for each cell line. Immunoblots were scanned by a UVP BioSpectrum AC image system and quantitated using VisionWork LS software. Columns, mean (n = 3); bars, SD.