Fig. 4. CFTR degradation is compromised in the add mutants. CFTR-expressing cells were grown to mid-log phase, cycloheximide was added, and the cells were harvested at the indicated time points. (A) Cell extracts were prepared at 0, 20, 40 and 60 minutes and subjected to SDS-PAGE followed by quantitative immunoblot analysis. (B) The relative amounts of CFTR were determined using the Bio-Rad Phosphor Analyses program with the amount of CFTR at the zero time point set at 100%. Results shown are the average of three independent experiments, ±s.d.