RBP4 and diabetic macular edema: Nakanishi et al. [21] observed the diabetic macular edema after proteomic analysis of vitreous and recorded six proteins including pigment epithelium derived factor (PEDF), ApoA-4, ApoA-1, thyroid hormone receptor interactor 11 (Trip-11), retinol binding protein 4 (RBP4), and vitamin D binding protein (VDBP) and only Apo H is present in nondiabetic controls.