So this is known as differential gene expression. So it's differential gene expression that allows cell one to follow pathway to and form a neuron while cell two follows pathway two to form a skeleton muscle cell. So it's differential gene expression that allows cell differentiation to actually take place. Now, what about cell determination? What exactly is the mechanism by which cell determination actually takes place? What is the mechanism by which that cell chooses that major to follow and then follows that major to produce that specialized type of cell?