Hierarchical cluster analysis distinguishes bone marrow– and peripheral blood–derived CD34⁺ cells.

All 18 CD34⁺ cells samples derived either from bone marrow or from peripheral blood were subjected to hierarchical cluster analysis on the basis of 51 differentially expressed genes displayed in Figure 2. Median-centered and normalized data are displayed using a color code, shown at the bottom of the figure. Red fields indicate higher values than median, green fields indicate lower values than median, and black fields indicate values that are equal to the median. The dendrogram visualizes the correlation of the different subgroups. Branch nodes connect closely related samples. The branch length indicates the degree of relationship. The shorter a branch is the more similar are the connected samples. Two main clusters are clearly distinguishable, the left one containing all 8 BM-CD34⁺cell samples and the right one containing all 10 PB-CD34⁺cell samples. Moreover, the right main branch distinctly separates 2 subclusters each with 5 PB-CD34⁺ cell samples.