R and Quelen. protein-coding genes, or polycistronic transcripts. They may be 1st transcribed as major microRNAs (pri-microRNAs) that match capped and polyadenylated transcripts of just one 1,000 nt. Pri-microRNAs are prepared in the nucleus from the RNase Drosha into 7080-nt, hairpin-shaped precursors, known as pre-microRNAs (1,2). They may be exported in the cytoplasm by exportin5 […]