<p>A hypothetical pathway of tumour evolution from a normal cell to an advanced-stage cancer. Mutations in key regulatory genes lead to changes in cell physiology that favour tumour growth. Over time, these genetic defects accumulate to confer many of the known hallmarks of cancer <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1003836#ppat.1003836-Hanahan2" target="_blank">[131]</a>. The sequence of these events and the timing represented here is only one example of how this might occur.</p
