Localization of CREB4, Luman, ATF6, OASIS, and CREBH. Cells grown on coverslips were transfected with 2 μg of the appropriate expression vector as indicated. At 24 h posttransfection, cells were fixed in methanol and stained with a monoclonal antibody that recognized the N-terminal epitope tag on each of the proteins (green channel), together with an antibody to the ER protein calreticulin (red channel).