Exendin-4 was further demonstrated to potentiate hepatic ATP-binding cassette transporter A1 (ABCA1) expression, which is known to influence hepatic cholesterol transportation and, in turn, partake in fatty liver disease, and to attenuate lipid accumulation via the Ca2+/calmodulin (CaM)-dependent protein kinase kinase/CaM-dependent protein kinase IV (CaMKK/CaMKIV) pathway [35]. Here, ABCA1 is linked to fatty liver disease.