Two well-understood sncRNAs in eukaryotic cells are: microRNA and siRNA. SncRNAs are small non-coding RNAs with the main function in the regulation of different stages in gene expression. micro RNA are involved in RNA silencing (negative gene expression) and post-transcriptional regulation of gene expression(microRNA is complementary to a part of mRNA and can inhibit translation of that mRNA). siRNAs also called silencing RNA because of their possibility to inhibit translation by degrading mRNA after transcription.