ERBB2 and breast cancer: Four BC cell lines with different molecular types (Luminal type A: MCF-7, Luminal type B: BT474, HER-2 overexpression type: MDA-MB-453, Triple-negative type: MDA-MB-231) were used in order to investigate the effects of differential expression levels of Cosmc on cellular functions, with the protein level of Cosmc in these four cell lines measured by Western blot.