MAPK3 and Hyperglycemia: On the other hand, significant hyperglycemia, elevated transcriptional expression levels of phosphenolpyruvate carboxykinase (pepck) and levels of phosphorylated extracellular signal-regulated kinase (ERK1/2), with additional reduced hepatic lactate/pyruvate (L/P) ratios can only observed in igf1-deficient females.