STEAP1 and prostate neoplasm: The responses to SPAS-1 was dominant over responses to other antigens, including Y-chromosome antigens SMCY, UTY, and EIAFIY, as well as responses to the six transmembrane epithelial antigen of the prostate (STEAP), which had been reported due to be immunogenic in male mice and selectively overexpressed in prostate tumors [20].