ERBB2 and breast cancer: Consistent with the level of hsa_circ_001783 in breast cancer samples, we found that hsa_circ_001783 was 2.5–3-folds higher in TNBC cell lines (MDA-MB-231, MDA-MB-468, and BT-549) than luminal and HER2-overexpression cell line (BT-474, MCF-7, T47D, and SK-BR-3) (Fig. 3a).