VTRNA2-1 is transcribed by RNA pol III and the transcript is ∼ 100 nt long. (A) VTRNA2-1 is transcribed by RNA pol III. T24 cells were treated with α-amanitin (RNA pol II inhibitor) and harvested at 24 and 48 hours after treatment. vtRNA2-1 is insensitive to α-amanitin treatment as are the known pol III transcripts (pre-tRNAtyr, vtRNA1-1, vtRNA1-2, and vtRNA1-3), while the formation of pol II transcripts is inhibited (GAPDH, pri-miR-21, pri-let-7a-3). (B) Expression of vtRNA2-1 in different cell lines by Northern blot analysis showing that very little is processed to the mature miR (21 nt). U6 indicates loading control; and miR-377, small RNA control.