Gene expression is controlled by regulatory factors. For example, to turn on Ras gene, it requires GTPase, meaning that GDP is phosphorylated to GTP, thus activating Ras pathway. It can be turned off by sensor molecules and other regulator factors.
This is not right. The Ras protein is activated/deactivated by exchange factors GAP and GEF. However, the Ras gene itself is not directly turned on or off. One should make a distinction between the _gene_ and the _gene product_ (or protein), as it pertains to the question of OP.