In cultured fibroblasts from 90.5 day old embryonic __SP__ , methylation of __SP__ __NODE__ gene is involved in methylation of a protein DNA complex consisting of DNA endogenous promoter from __SP__ __NODE__ gene and of __SP__ __NODE__ to a protein DNA complex consisting of DNA endogenous promoter from __SP__ __NODE__ gene and of methylated ( K4 ) __SP__ __NODE__ that involves mutant __SP__ __NODE__ gene ( homozygous knockout ) and mutant __SP__ __NODE__ gene ( homozygous knockout ) .