RARS1 and hypervitaminosis A: Under slight dietary hypervitaminosis A (1.5×VA group) conditions, an increase in RBP mRNA level could be directly induced by binding of ligand activated RARs and RXRs to its RARE [51]; whereas during exposure to elevated VA levels (10×VA group), a decrease in RBP expression might take place to reduce the mobilization of VA from the adipose tissue and liver [52].