Finally, while our data strongly suggest that both ATF6α and ATF6β are important for the development of compensatory cardiac hypertrophy following pressure overload stress, it is unclear whether the major activities of these proteins are confined to myocytes, or if they also play important roles in other cell types in the heart such as cardiac fibroblasts, endothelial cells, and immune cells. Here, ATF6B is linked to cardiac hypertrophy.