MAPK3 and cardiac hypertrophy: For example, binding of Ang II to the AT1 receptor on cardiomyocytes activates NADPH oxidase, which increases superoxide (ROS) production and activates signaling proteins in cardiomyocytes, such as ERK1/2, p38 MAPK, JNK, and Akt, which increase protein synthesis and gene expression, thereby increasing the size of cardiomyocytes and contributing to the formation of cardiac hypertrophy [21,22].