Potential explanation of the difference in MS hit numbers found between T47D and H1299 cells would be the origin of the cell lines: breast cancer cell line T47D versus H1299 lung carcinoma cell line and/or the nature of the AGR2 protein expression: very high endogenous level in T47D in comparison to artificial AGR2 expression in H1299 cells stably transfected with the vector carrying AGR2 coding sequence (Fig. 1, B and C). This evidence concerns the gene AGR2 and breast cancer.