RCN1 is a Ca2+ -binding protein, involved in endoplasmic reticulum stress, highly expressed in several malignant tumors like breast cancer, colorectal cancer, naso-pharyngeal carcinoma or non-small cell lung carcinoma [11, 17, 26, 27] associated either with poor prognosis or therapy resistance. This evidence concerns the gene RCN1 and breast carcinoma.