Although all the cell lines expressed HER2, the patterns of hormone receptor expression and cancer-related gene expression, HER2 expression level, and mutation profile of tumor suppressor genes vary by cell line (American Type Culture Collection (ATCC); Cancer Cell Line Encyclopedia (CCLE)) [34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49] (Table 2 and Table S2). The gene discussed is ERBB2; the disease is neoplasm.