Pre-MIR886/VTRNA2-1 lacks a pri-miR transcript and is independent of Drosha. (A) Map and genomic sequence showing pre-MIR886/VTRNA2-1, mature “MIR886-5p and -3p” and the transcription start site (TSS) as determined by 5′ RLM-RACE in T24 cells. Pre-MIR886/VTRNA2-1 is depicted as the black line in the map and the gray lines represent the mature MIR886. The tick marks represent individual CpG sites. The CpG island is labeled on the map by the gray bar. The TSS is shown as the arrow. (B-C) Processing of vtRNA2-1 is independent of Drosha. T24 cells were transfected twice with Drosha siRNAs, and collected 72 hours after the second transfection. (B) Drosha protein levels were detected by Western blots. (C) Stem-loop RT-PCR show unchanged levels of mature “miR886-5p and -3p,” while miR-21 expression is inhibited by Drosha knockdown.