Figure 2. Squamous, small cell, and large cell lung tumors express a unique set of genes. A) Hierarchical clustering sorted 918 cDNA clones and 73 lung tissues based on similarity in gene expression. Gene clusters relevant to lung tumor types were extracted from the larger cluster of 918 clones in the regions indicated by the colored bars in A) and expanded on the right to include gene names. A row in the cluster indicates expression of a specific gene across all 73 lung tissues. A column indicates the tissue in which the gene is expressed. Red, green, and black squares indicate that expression of the gene is greater than, less than, or equal to the median level of expression across all 73 lung tissues, respectively. Grey represents missing or poor quality data. B)(top) Gene clusters relevant to large cell tumors (blue bar). (middle) Gene clusters relevant to small cell tumors (yellow bar). (bottom) Gene clusters relevant to squamous lung tumors (red bar). The scale bar (lower bottom) reflects the fold increase (red) or decrease (green) for any given gene relative to the median level of expression across all samples.