The answers of this question are the following:
(1) a growth factor that binds to
(2) its receptor in the plasma membrane.
The signal is relayed to (3) a G protein called Ras. Like all G proteins, Ras is active when GTP is bound to it.
Ras passes the signal to (4) a series of protein kinases.
The last kinase activities (5) a transcription activator that turns on one or more genes for proteins that stimulate the cell cycle. If a mutation makes Ras or any other pathway component abnormally active, excessive cell division and cancer may result.
