Mutant __SP__ __NODE__ gene ( homozygous knockout ) in __SP__ skeletal muscle decreases phosphorylation of __SP__ __NODE__ protein in isolated extensor digitorum longus muscle from 7 10 week old __SP__ to phosphorylated ( S212 ) __SP__ __NODE__ protein in isolated extensor digitorum longus muscle from 7 10 week old __SP__ that is increased by phenformin in culture medium .