Binding of a protein chimera composed of a protein fragment containing a cytosolic tail domain from __SP__ __NODE__ protein and of a protein fragment containing a lumenal domain and a transmembrane domain from __SP__ __NODE__ protein and ear domain from __NODE__ protein does not occur in mutant Mef cells with a homozygous knockout of __SP__ __NODE__ and a homozygous knockout of __SP__ __NODE__ .