These IRCS go into the cell nucleus and they activate transcription factors. These transcription factors then move on and express different types of genes that produce mRNA molecules which then exit the cell and they essentially are used by the ribosomes to produce proteins. The proteins are in turn used to basically build up the cytoplasm, build up the cytoskeleton which basically increases the size of the cell and that cell eventually is able to divide. And so in this process, the EGF signal transduction pathway stimulates cell differentiation, cell growth and cell proliferation of two types of cells, epidermal cells and epithelial cells. Now, once this pathway actually carries out its specific purpose, how exactly does a normal cell terminate this process? Well, there are three major methods.