There is a redundant function between FABP4 and FABP5, as Fabp4 and Fabp5 (Fabp4/5 double-knockout (DKO) mice) exhibited a dramatic phenotype related to protection against obesity, insulin resistance, atherosclerosis, and fatty liver disease compared to Fabp4-/- or Fabp5-/- mice [59,60]. Here, FABP4 is linked to obesity due to melanocortin 4 receptor deficiency.