The importance of the antizyme 5 0 sequence context to antisense oligonucleotide induced ribosome frameshifting was examined by testing the frameshift site, UCC UGA, without the 5 0 and 3 0 stimulatory antizyme sequences. To this end, the 5 0 antizyme stimulatory sequences were deleted from p2luc-AZ1PKdel to make p2luc-AZ1FS. Each of the antisense oligonucleotides AZ1A, AZ1B or AZ1C was added to coupled transcription and translation reactions with p2luc-AZ1FS in the presence or absence of spermidine. Frameshift efficiency was measured at 11, 8 and 4%, in the presence of spermidine and 3, 0.4 and 0.2% in its absence for AZ1A, AZ1B and AZ1C, respectively ( Figure 5A and B) .