89. Which step about regulation of gene expression by insulin is not correct? (A) Insulin receptor binds insulin and undergoes autophosphorylation. (B) Insulin receptor binds IRS-1 on its Tyr residues. SH3 domain of Grb2 binds to phosphorylated Tyr of IRS-1. (C) Sos binds to Grb2, then to Ras, causing GDP release and GTP binding to Ras. (D) Activated Ras binds and activates Raf-1. (E) Raf-1 phosphorylates MEK. MEK phosphorylates MAPK, activating it.