ERBB2 and breast cancer: In addition, silencing HER2 gene in SK-BR-3 cells and over-expression of HER2 gene in HER2– BC cells (MCF- 7 and MDA-MB-231) had no effect on expression of circCDYL, indicating that HER2 gene do not regulate the expression circCDYL in HER2+ cell (Supplementary Figures 1A,B).