Selected molecular marker expression by immunohistochemistry (IHC).

<p>P53 in Line A and Ki-67 in Line H are examples of similar expression between patient, early passage (P1) and latest passage (P_{<i>latest</i>}) xenografts. P16 in Line H was selected to demonstrate the heterogeneity detected in the same tissue (P_<i>early</i> showing both positive and negative expression). EGFR expression in Line E exhibited an increase in intensity from patient to xenografts while Her-2/<i>neu</i> expression in Line A showed a decrease in intensity. These examples were included to demonstrate that the differences exhibited between patient tissue, early passage and latest passage xenografts were due to intrinsic heterogeneity and not to any specific patterns of expression.