In the context of the emerging literature on the role of PDIA17 in tumorigenesis, based on our proteomic analysis confirmed by Western blotting, we were able to clearly define MCF-7 as a breast cancer cell line with high PDIA17 expression, whereas MDA-MB-231 had very low PDIA17 expression, and we used these two cell lines for pharmacological studies. The gene discussed is AGR2; the disease is breast cancer.