(a) P2 template derivatives containing various insertions (underlined) at position +37 or G to T substitutions (bold underlined T), some of which mimic wt sequence. (b) RNA made from templates containing 5- or 10-bp insertion (∇5 (lanes 1, 2), ∇5G (lanes 3, 4) and ∇10C (lanes 5, 6)). (c) RNA made from templates containing G to T substitution at position +34 and/or +36 (∇5 (lanes 1, 2), ∇34T (lanes 3, 4), ∇36T (lanes 5, 6), and ∇34T36T (lanes 7, 8).