BRCA1 and breast cancer: In liver cancer cells, transforming growth factor beta 1 (TGF-β1) indirectly promotes epithelial-mesenchymal transition (EMT) and CSC phenotypes through down-regulation of TP53INP1 by miR-155 [53] while in breast cancer, miR-155 is involved in tumor initiation via transcriptional repression of BRCA1 [54].