Plotting of the position of the first base (5' end) of Alu RNA fragments across the Alu consensus sequence produced by Alu RNA that has been processed in vitro for 90 minutes at 37C in the presence of HSF1 (upper panel) and compared with one of the in vivo samples of Figure 1 (lower panel). The x axis represents an Alu RNA metagene aligned at the start site of the Alu consensus sequence and the y axis shows the 5' end count for Alu RNA fragments aligning to any position downstream of position +1. The in vivo sample x axis depicts a 11nt sift compared to the in vitro one. 