Comparison of normal cells vs. cancerous cells.
Unknown author<span style="display: none;">Unknown author</span>
<a rel="nofollow" class="external text" href="http://press2.nci.nih.gov/sciencebehind/cancer/cancer22.htm">National Cancer Institute</a> (<a rel="nofollow" class="external text" href="https://web.archive.org/web/20041021115221/http://press2.nci.nih.gov/sciencebehind/cancer/cancer22.htm">archived</a>)