How does a protein kinase cascade amplify an intercellular signal?

The answer is; One activated receptor kinase molecule can trigger the activation of thousands of proteins. This is also true for other signal transduction cascades. When a signal molecule binds to the receptor, secondary messengers are activated inside the cell. In every step is the cascade, the signal is amplified multiple times.

Through external signaling, the protein kinase cascade controls the activity of enzymes through phosphorylation of enzyme proteins.