On the cover: Immunohistochemical labeling for pendrin (blue label) and mineralocorticoid receptor (MR, brown label) in the cortical labyrinth from an intercalated cell-specific MR null mouse fed a NaCl-deficient diet. As shown, apical pendrin distribution in MR(+) intercalated cells (arrows) is strong and distinct, whereas in MR(-) intercalated cells (arrowheads), pendrin immunolabel is less abundant and more diffusely distributed through the cell cytoplasm. Image supplied by Susan Wall, Emory University, Atlanta, Georgia