SSTR2 and neoplasm: Given the binding activity of DTPA-R for an exogenous hapten, interferences with cellular processes are much less likely than for reporter proteins that lead to ion transport over the cell membrane (NIS), represent tumour-associated surface antigens (tPSMA and SSTR2) or possess catalytic activities (HSV-tk, tPSMA, SNAPtag and eDHFR).