PTGER4 and cardiac hypertrophy: It has been recognized that COX2/PGE2 pathway plays critical roles in cardiac hypertrophy.13, 14 Previous study found that overexpression of COX2 leads to substantially elevation of cardiac PGE2 and cardiomyocyte hypertrophy in a genetic mouse model.13 The present study showed that Ang II up‐regulated COX2 and PGE2 along with its downstream signalling molecules (EP4 and pERK) in in vivo and in vitro, which was reduced by NaBu treatment (Figures 4, 5, 6, 7).