Genna is describing an experimental result in which a metabotropic receptor activated multiple proteins. Genna is describing a(n):

Amplification cascade

Explanation:

Amplification cascade also known as Signaling pathway occurs when a stimulus or first messenger prompts a biological reaction within a cell which in turn acts on a receptor that undergoes signal transduction and amplification caused by secondary messengers. These secondary messengers send the signal to the effector sites who now produce a response to the initial stimuli.

So, the basic principle of an amplification cascade is the fact that a particular action triggers the response of several other factors. This is similar to what Genna describes in her experiment where a metabotropic receptor activated multiple proteins.