RBP4 and Insulin resistance: proposed another mechanism by which RBP4 affects insulin resistance, namely that RBP4 can bind to STRA6, trigger its phosphorylation, and recruit and activate Janus kinase 2 and signal transducer and activator of transcription 5, which causes the upregulation of genes such as cytokine signalling suppressor 3, thereby inhibiting insulin signalling (40).