Figure 1.

Comparison of the current subtyping schemes between breast cancer cell lines and tumors. According to the status of ER, PR, HER2, breast cancer is classified as luminal A, luminal B, HER2 positive, and triple negative, where triple negative tumors can be further differentiated into at least basal, claudin-low, MBC (metaplastic breast cancer) and interferon-rich. The current literatures, in general, do not differentiate luminal cell lines; HER2 positive cell lines are diffused into luminal B and triple negative cells, and named luminal-HER2+ and ER-negative-HER2+, respectively; and triple negative cells are called the 'Basal' subtype, with basal A and basal B being further differentiated to represent the basal tumors and claudin-low and/or MBC tumors, respectively. The morphological features of the subtypes in tumors and cell lines accord well, with luminal tumors having better prognosis and luminal cell lines less aggressive than that in triple negative tumors and cell lines.