Sumoylation of ATF6 in the human tracheal cell line stably expressing CFBE41o-WT CFTR or CFBE41o-dF508CFTR. Total cellular lysates from CFBE41o-WT CFTR- or CFBE41o-dF508CFTR-expressing cells were immunoprecipitated using the anti-AFT6 antibody, and then probed with the anti-SUMO1 antibody to detect the sumoylated ATF6 protein (Upper panel). Expression of CFBE41o-WT CFTR and CFBE41o-dF508CFTR was detected by Western blot analysis using the anti-CFTR antibody (middle panel). The wild-type (WT) CFTR protein displayed C band (full glycosylation form, material band) and B band (core glycosylation form, immaterial band), and the dF508CFTR protein displayed B band and A band (none glycosylation form). As the control, expression of total AFT6 protein was also detected by Western blot analysis (lower panel). The graph beside the image showed the quantification of fold changes of sumoylated ATF6 potein levels, as determined by Western blot densitometry, in the CFBE41o-WT CFTR- or CFBE41o-dF508CFTR-expressing human tracheal cells.