A radiotherapeutic agent comprising a 32P or 33P radiolabeled protein selected from the group consisting of:wherein X is an targeting peptide, Y is a phosphorylation peptide, L is a flexible linker, preferably a peptide linker, and SH2 represents an SH2 domain; whereby said phosphorylation peptide is radiolabeled with 32P or 33P
Stabilized radiophosphate-labeled proteins