Now, anytime either one of these two cell types is damaged in some way for instance I may make some type of cut in my skin so that the epidermal cells are damaged. What happens is a molecule known as epidermal growth factor is released and this molecule is a peptide molecule. It's a protein that acts as a primary messenger in the EGF signal transduction pathway where EGF stands for epidermal growth factors. So this is a signal transduction pathway that we're going to focus on in this lecture. So we see that this pathway stimulates the growth and division. So processes like cell proliferation, cell division, cell growth, cell differentiation of these epidermal and epithelial cells.