Dominant-negative hook2 proteins do not alter the biochemical properties of CFTR. (A) Western blots indicate that co-expression of hook2 truncations did not significantly change the ratio of CFTR in the high (**) to low-molecular mass (*) bands or the detergent solubility of ΔF508-CFTR. (B) Western blots of homogenates of cells co-transfected with CFTR and various hook proteins or controls showed that steady state levels of wt CFTR or ΔF508-CFTR were not altered by the indicated hook proteins. Band C is the mature CFTR protein and band B the core glycosylated form . Equivalent loading was assured by evaluation of protein concentrations in cell lysates using the DC Protein Assay from BioRad. 20 μg total protein was loaded per well.