text: why ncrnas cannot be knock down by rnai technique? many scientist reason out for this is to be proteins which binds these ncrnas. is there any other reason for this? the second part of your question is a bit hard to decipher, but i'm going to take a shot. why can't non-coding rnas be knocked down by sirna? sirna prevents a messenger rna from being expressed as a protein. a non-coding rna, by definition, does not code for a protein. knock down is at the protein level, and if there is no protein expected to be made, why would you expect to knock it down?  if you wanted to ask whether non-coding rnas could be eliminated by a method similiar to sirna...one difference between small interference rnas and micro rnas is how they affect the mrna transcript, and i always mix these up, so i'll leave it to you to look it up if you're interested. one binds the mrna and prevents its translation, but leaves the mrna intact. the other causes it to be degraded. if you wanted to "knock down" non-coding transcripts, it seems like it could conceivably be done with the method that causes degradation of the transcript. but it woud have to be tested.