Which of the Following Statements Concerning Signal Transduction by the Insulin

Which of the following statements concerning signal transduction by the insulin receptor is not correct?

A) Activation of the receptor protein kinase activity results in the activation of additional protein kinases.
B) Binding of insulin to the receptor activates a protein kinase.
C) Binding of insulin to the receptor results in a change in its quaternary structure.
D) The receptor protein kinase activity is specific for tyrosine residues on the substrate proteins.
E) The substrates of the receptor protein kinase activity are mainly proteins that regulate transcription.