Representative charts of response surface.

<p>Response surface shows the effects and interactions of Glu and Asp, Arg and Asp, Gly and Asp, Arg and Glu, Gly and Glu, Gly and Arg on the final mAb titre response. (For instance in part B, if Asp and Arg concentrations become less or more than the middle point (0), the response will reach the maximum amount. These changes should be the same for both amino acids. It means Asp and Arg should increase or decrease in one direction and if both of them decrease, the response will be better. Also in part C, if Asp and Gly concentrations increase toward +1, the response will reach the maximum amount.)