Effect of VX-445-based treatments on mutant CFTR half-life. (A) Immunoblot detection of CFTR in whole lysates derived from wild-type or F508del-CFTR expressing CFBE41o- cells treated with vehicle alone (DMSO), or (for mutant CFTR only) with VX-445 (3 µM), VX-809 (3 µM), or VX-661 (10 µM) as single agents or combinations, at different time points following CHX-induced block of protein synthesis. For comparison, whole lysates derived from CFBE41o- cells not expressing CFTR (null cells) are also shown as controls for antibody specificity. (B) Quantification of wild-type or mutant CFTR (band B and band C) half-life in experiments detailed in (A), normalized by the value at time = 0. Data are means ± SD (n = 3). Dashed lines indicate 50% of the protein remaining (y-axis) and the corresponding intercepts on the x-axis, indicating the estimated half-life.