To assess the clinical relevance of STEAP4 in BC and normal breast tissues, IHC analysis of STEAP4 was conducted initially on tissues derived from mice inoculated with the HCC-1954 and MDA-MB-231 cell lines and on two independent BC TMAs (BRC253, BRC961) containing a total of 18 benign and 42 malignant breast tissues. This evidence concerns the gene STEAP4 and breast cancer.