Ziegler et al. (2016) used mass spectrometry to identify proteins secreted from three TNBC cell lines (DT22, DT28, and MDA-MB-231) compared to a luminal-type cell line with normal expression of the ER, PR, and HER2/Neu (MCF-7) and a non-tumor cell line. The gene discussed is ESR1; the disease is neoplasm.