RBP4 and atherosclerosis: Retinol binding protein 4 (RBP4), a transport protein belonging to the lipocalin family, is implicated in the incidence and progression of atherosclerosis by inducing macrophage-divided foam cell formation and regulating the Janus kinase 2/signal transducer and activator of transcription 3 (JAK2/STAT3) signaling pathway (11–14).