<n0:ComplexDefinition xmlns:n0="http://ncicb.nci.nih.gov/xml/owl/EVS/ComplexProperties.xsd#"><n0:def-definition>A radioimmunoconjugate composed of the radioisotope zirconium Zr 89 conjugated to an antibody that targets six transmembrane epithelial antigen of the prostate 1 (STEAP1) that can potentially be used as a prostate cancer tracer during positron emission tomography (PET). Upon administration of zirconium Zr 89 DFO-MSTP2109A, the antibody moiety DFO-MSTP2109A binds to STEAP1 on prostate cancer cells. In turn, Zr 89 allows for the visualization of those cells using PET. STEAP1, a six-transmembrane domain protein, is overexpressed on the surface of prostate cancer cells.</n0:def-definition><n0:def-source>NCI</n0:def-source></n0:ComplexDefinition>