RHEB and cardiac hypertrophy: In that study, using mice in which ATF6 was deleted specifically in cardiac myocytes, it was shown that ATF6 transcriptionally induces the small GTP binding protein, Rheb, which is an activator of mTORC1 (Figure 2A, Cardiac Hypertrophy), a well-studied pathway responsible for myocardial growth during development and pathology, thus describing Rheb as a non-canonical adaptive UPR gene induced during cardiac hypertrophy.