Which of the following correctly describes the sequence of events in the insulin signaling cascade?

• A. Insulin binds to RTK, RTK autophosphorylates, IRS 1 is phosphorylated, PI3K is activated, PIP2 is converted to PIP3, PKB is activated.
• B. Insulin binds to RTK, RTK inhibits IRS 1, PI3K is phosphorylated, PIP3 is converted to PIP2, PKB is degraded.
• C. Insulin binds to RTK, RTK activates IRS 1, PI3K is degraded, PIP2 is phosphorylated, PKB is inhibited.
• D. Insulin binds to RTK, IRS 1 is degraded, PI3K is inhibited, PIP2 is hydrolyzed, PKB is inactivated.

Answer: (A)