Which Process Is NOT an Event in the Signaling Pathway

Multiple Choice

Which process is NOT an event in the signaling pathway from insulin to glycogen synthase kinase 3 (GSK3) inactivation?

A) insulin binding to a tyrosine kinase receptor
B) activation of insulin receptor substrate-1 (IRS-1) by phosphorylation
C) phosphatidylinositol 3-kinase associating with IRS-1 generates phosphatidylinositol 3,4,5-triphosphate
D) protein kinase B being activated by a protein kinase known as PDK-1
E) protein kinase B phosphorylating GSK3, resulting in its activation