RBP4 and Insulin resistance: Insulin resistance (accompanied by other diabetes-related conditions, such as obesity, adipocytokines secreted by adipocytes and macrophages in adipose tissue, interleukin (IL)-6, tumor necrosis factor (TNF)-α, leptin, retinol binding protein-4, lipocalin-2, and adiponectin that may aggravate insulin resistance) plays a detrimental role in the biology of a tumor and its progression [19,20,21].