AKR1C3 and neoplasm: Interestingly, increased mRNA expression of several steroidogenic enzymes (i.e., 3βHSD, CYP17A1, AKR1C3, and SRD5A2) accompanied the increased testosterone concentrations found within metastatic CRPC foci—providing a mechanistic explanation for why increased androgens levels are found within the metastatic tumor microenvironment (Fig. 2).