Academic Editor: Allan C. Peterson
Copyright © 2011 Bao Shi et al. This is an open access article distributed under the
Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
A mathematical model for growth of tumors with two discrete delays is studied. The delays,
respectively, represent the time taken for cells to undergo mitosis and the time taken for the cell to
modify the rate of cell loss due to apoptosis and kill of cells by the inhibitor. We show the influence
of time delays on the Hopf bifurcation when one of delays is used as a bifurcation parameter.