We next compared luciferase expression in doseresponse experiments in saponin-treated and untreated cells. As shown in Figure 7 for the (R-Ahx-R) 4 -PMO conjugate, splicing correction was more efficient in saponin-treated than in untreated cells. Significant luciferase expression could already be detected upon 30 min incubation in saponin-treated cells and increased to a much higher level than in untreated cells. In addition, splicing correction in saponin-treated cells reached similar levels for conjugates found much less active in nonpermeabilized cells than (R-Ahx-R) 4 -PMO ( Figure 7B) .