To better understand the potential role of CEP55 in breast cancer, we transiently knockdown CEP55 with pooled siRNAs in a panel of breast cancer lines and noticed significantly reduced viability of 6/8 basal and 4/9 luminal/HER2 cell lines with cutoff of 50% inhibition, irrespective of their baseline CEP55 expression (Figs 1C and EV2A). This evidence concerns the gene ERBB2 and breast cancer.