Potency of FLAG-ATF6(1–373)-[67]-methionine, FLAG-ATF6(1–373)-[67]-valine, and FLAG-ATF6(1–373)-[67]-leucine to induce endogenous GRP94 and GRP78 levels. Panel A: Hela cells, transfected with one of the FLAG-ATF6(1–373) plasmids (1µg) were extracted and analyzed for expression of FLAG-ATF6, Grp78, Grp94 and GAPDH by western blot using specific antiserum antibodies for FLAG, KDEL (Grp78 and Grp94), and GAPDH, respectively. Panel B: quantification of the blots by densitometry analysis. Each value represents the mean and SEM of 4 independent transfections). * p<0.05, # p<0.01