Taken together with the recent identification of PROX1 as an important regulator of the ERRα/PGC-1α axis involved in the regulation of broad transcriptional programs implicated in the control of energy homeostasis in the liver [34] and the observation that the PROX1 locus is associated with fasting glucose levels and increased risk for type II diabetes [35], this study implies that PROX1 possesses all the necessary attributes to be an important factor linking metabolism and circadian rhythms. This evidence concerns the gene ESRRA and type 2 diabetes mellitus.