S1PR1 and cardiac hypertrophy: In mouse experiments, S1PR1 expression is upregulated during myocardial hypertrophy and can lead to myocardial hypertrophy and fibrosis by inducing interleukin (IL)-6 secretion in a manner dependent on Ang II-AT1, though this occurs only in proliferating fibroblasts and not in cardiac myocytes [131].