STEAP1 and cancer: Six-transmembrane epithelial antigen of prostate-1 (STEAP1), also known as PRSS24, belonging to the STEAP family, is a cell surface antigen overexpressed in various tumors and is closely associated with the prognosis of numerous malignant tumors (Grunewald et al., 2012a; Ihlaseh-Catalano et al., 2013; Lee et al., 2016; Barroca-Ferreira et al., 2018).