Figure 6. p35 siRNA had a similar biological effect to the treatment with CDK5 inhibitors. LLC–PK1 cells were untreated or transfected with control (random) or p35 specific siRNA. After 24 h of silencing, cells were treated as indicated in Figure 1. (A) The caspase-3/7 activity of the cytosolic cell extracts was measured. In all cases, bars represent the mean of 3 experiments ± sd. (B) The cellular extracts of the LLC–PK1 cells treated as described above were analyzed by western blot for the expression of p35/p25, CDK5 and cyclin I. A densitrometric analysis of the western blots from 3 independent experiments are shown in the right panels.