Fig. 3.

A two-step enrichment was adapted in the statistical analyses to identify the common transcriptional alteration in all osteosarcomas and to filter out factors contributed by the individual samples possibly owing to the microenvironment. In Step 1, each osteosarcoma SAGE library was compared with that of osteoblasts and MSC89R independently. Genes (tags), which were differentially present between tumor and normal, are pooled together. A second step identifies genes, which are commonly downregulated in osteosarcoma compared with normal osteoblasts (OB) and MSC89R.