GCK and Hyperglycemia: Glucokinase (Gck), the first rate-limiting step in glucose metabolism, however, was decreased expression in the liver of Gprc6aLiver-cko consistent with the observed reduced glucose 6-phosphate levels and mild hyperglycemia associated with inactivation of GCK20; but genes that regulate glycolysis, including Gpi, Pdha1, Pdhb, Pklr, Slc2a3, Aldoa, Aldob, Pgam1, Pfkl, Pgm1, Pdhx and Creb1, expression were increased in the liver of Gprc6aLiver-cko.