Now, the second important point of the solid phase method is we have to use different types of molecules, activating and blocking agents to basically promote that particular reaction, the formation of peptide bond that we actually want to form. So in step number one, in order to promote and increase the specificity of the reaction and decrease the number of unwanted products from actually forming, we have to use these different types of molecules to direct the correct synthesis of the protein. Because remember, in any given amino acid, we have different types of groups and these different types of groups react in different ways. And so we can have a variety of different types of competing reactions and competing products. And to basically minimize these unwanted products, we have to use two important agents. One of them is DCC, and that's an activating agent and it activates the carbon atom on the carboxyl group of the amino acid.