For example, lower serum levels of retinol binding protein 4 (RBP4) are detected in CG and are related to gallstone formation, and decreased RBP4 level was independent on renal function in CG patients  (Wang et al., 2010). The lithogenic diet can result in significantly lower cholecystokinin A receptor (CCKAR) and caveolin-3 (CAV3) in the gallbladder and lower CAV3 in the liver, indicating that CAV3 and CCKAR may be implicated in CG (Xu et al., 2014). Here, CCKAR is linked to gallstones.