STAT3 and breast cancer: Sorafenib, SC-1 and SC-43 induced apoptosis, concurrent with downregulation of p-STAT3 and its downstream proteins, cyclin D1 and survivin, dose-dependently in BC cell lines (HCC-1937, MDA-MB-468, MDA-MB-231, MDA-MB-453, SK-BR3 and MCF-7).