Gene expression analysis of engrafted AML cells. A dendrogram is shown from the unsupervised hierarchical cluster analysis of the 8 chips for the 2260 genes passing the variation filter. Independent of karyotype, AML patients were grouped between before and after engraftment. This means that the AML in the original patient is very much related to the AML that has grown in the mouse. The samples corresponding to before and after engraftment were always adjacent to each other, reflecting a very close relationship between them. Pt indicates patient. Height is an arbitrary unit of association; higher numbers indicate greater degree of similarity.