The frequency with which a union goes out on strike is a good measure of the bargaining strength of that union.

In certain cancerous cells, the cell divides continuously even in the absence of a growth factor (signaling molecule) that indicates the cell should divide. Which of the following could explain this?

A) a receptor molecule that is always turned on
B) a receptor molecule that is always turned off
C) a transduction pathway that is always turned off
D) a target protein that is always deactivated
E) a gene for cell division that is not expressed when it should be