ERBB2 and breast cancer: To accomplish this we queried our RNA-seq dataset of 57 breast cancer cell lines with known subtype and HER2/ERBB2 status and found that: (a) PADI2 expression is highest in luminal cell lines and that (b) PADI2 expression is highly correlated with HER2/ERBB2 overexpression across the basal-NM, claudin-low, and luminal lines.