Remarkably there was no correlation between the T m of the LNA oligonucleotides and their frameshifting inducing capacity. For example, the T m of LNA2 was rather low with 76 C but it had the highest frameshifting activity, and L2-2, which had the highest T m , actually had the lowest frameshifting activity. T m s of L2-3 and L2-4 were identical but their frameshifting activities were 2.3 and 4.6%, respectively. We also noted that both L2-2 and L2-3 were comparable to DNA18 in frameshifting activity but formed far more stable duplexes. These data suggest that the position effect of the LNA substitutions is related to the mechanism of frameshifting and not per se to their thermodynamic stability.