A, effect of Hsp27 knockdown and correctors on the ΔF508-CFTR mutant. HEK-293 cells stably expressing ΔF508 were transfected with siRNA Hsp27 (10 nm) for 72 h. Subsequently, cells were treated with C4 (10 μm) and C18 (10 μm) for 16 h. B, data summarizing the densitometry measurements of immunoblots. Data are normalized to untreated (white bars). Versus untreated: *, p < 0.05, **, p < 0.01. Versus siRNA Hsp27: #, p < 0.05 (n = 4). C, CFBE cells stably expressing ΔF508 were transfected with siRNA Hsp27 (10 nm) for 72 h. Subsequently, cells were treated with C4 (10 μm) and C18 (10 μm) for 16 h. D, data summarizing the densitometry measurements of immunoblots. Data are normalized to untreated (white bars). Versus untreated: *, p < 0.05; **, p < 0.01. Versus siRNA Hsp27: #, p < 0.05 (n = 4). Ezrin (Ez) was used as a loading control.