Mutant __SP__ __NODE__ gene ( unspecified homozygous gene mutation ) decreases __NODE__ phosphorylation of __SP__ IGF __NODE__ [__NODE__] protein in fibroblast cell lines from __SP__ exhibiting ataxia telangiectasia to phosphorylated ( Y ) __SP__ IGF __NODE__ [__NODE__] protein in fibroblast cell lines from __SP__ exhibiting ataxia telangiectasia that is increased by __NODE__ protein in culture medium .