The diagram above represents a model of signal transduction pathways (I and II) in a cell that is targeted by two different hormones (H, and H.). The components of the signal transduction pathways are identified in
the figure legend. Each cellular molecule in both pathways can exist in an inactive or active form. When the
components in pathway I are sequentially activated, the TAP molecules promote cell division. When the
components in pathway II are sequentially activated, downstream signaling by the G protein is inhibited.
Based on the model, which of the following mutations is most likely to result in a cell that will generate a
cancerous tumor?