In __SP__ 1 cells , the affinity of binding of heterodimer consisting of __SP__ __NODE__ and of mutant __SP__ __NODE__ ( C terminal truncation 978 End with its autophosphorylation site and its __NODE__ domain deleted ) and Igf 1 [__NODE__] protein is the same as the affinity of binding of dimer consisting of __SP__ __NODE__ and Igf 1 [__NODE__] protein .