<span>I believe it is light, but this is kind of a confusing question. Technically there is a independent and dependent variable in the question. The variable being manipulated is light, and the earthwork activity depends on the light. </span>
Using the gas pedal analogy, the proto-oncogene would be an accelerator since they promote cell division and
deregulate apoptosis, while tumor suppressor would
be the brakes since they constrain the progress of the cell
cycle and induce cell apoptosis. An
oncogene is, therefore, when the accelerator
is stuck in down position and the brakes are not working.