Dicer-1 and Dicer-2 have different ATP requirements. (a) Dicer-1 processes pre-miRNA into miRNA in an ATP-independent manner. The pre-miRNA-processing assays were performed with 0.03, 0.1, 0.3, 1 nmol recombinant Dicer-1 in the absence (lanes 1–4) or presence (lanes 5–8) of ATP. (b) Dicer-1 cleaves dsRNA into siRNA in an ATP-independent manner. The dsRNA-processing assays were performed with 0.03, 0.1, 0.3, 1 nmol recombinant Dicer-1 in the absence (lanes 1–4) or presence (lanes 5–8) of ATP. (c) Dicer-2 requires ATP for efficient siRNA production. The dsRNA-processing assays were performed with 1.25, 2.5, 5, 10 pmol recombinant Dicer-2 in the absence (lanes 1–4) or presence (lanes 5–8) of ATP.