Mutant __SP__ __NODE__ gene ( homozygous knockout ) in __SP__ and mutant __SP__ __NODE__ gene ( homozygous knockout ) in __SP__ decrease phosphorylation of __SP__ __NODE__ [__NODE__] protein in fibroblasts from embryonic __SP__ to phosphorylated ( S307 ) __SP__ __NODE__ [__NODE__] protein in fibroblasts from embryonic __SP__ that is increased by __NODE__ protein in cell culture .