To confirm the specificity of [89Zr]Zr-DF'-GGSK-1/30 for hu(TA)MUC1 in vivo and to assess its usage as a future diagnostic tool for huMUC1-expressing breast cancers, the radioconjugate was administered i.p. in C57BL/6N mice bearing PyMTxhuMUC1 breast tumor cells subcutaneously on the right flank. This evidence concerns the gene MUC1 and breast carcinoma.