miR-133a/b have been demonstrated to be involved in cardiac hypertrophy; indeed, an miR-133 decrease positively regulates cardiac hypertrophy, increasing the expression of its targets, including calcineurin, NFATc4 (regulator of hypertrophy), Rac, and Cdc42 (regulators of cardiac prohypertrophic mitogen-activated protein (MAP) kinase pathway [84]. The gene discussed is CDC42; the disease is cardiac hypertrophy.