(F) Association of increasing Htt-552 with isolated lysosomes untreated (Binding) or pre-treated with protease inhibitors (Binding+Uptake) at 5, 10 and 20 min. Values are the mean±SE of three independent experiments. **P<0.01 (compared with Htt-552-18Q without treatment); ##P<0.01 (compared with Htt-552-100Q without treatment). 