FOXO4 and heart disorder: There are four members of the FOXO family in mammals, namely, FOXO1, FOXO3a, FOXO4, and FOXO6; FXOXO1 is highly expressed in adipose tissue, heart, brain, and skin, FOXO3a is highly expressed in skeletal muscle, myocardium, and neurons, FOXO4 is highly expressed in myocardium, and FOXO6 is only expressed in specific regions of the brain; FOXO3a is the most abundantly expressed subtype in the heart and is the most important potential target for the treatment of cardiac diseases.53