Hierarchical clustering analysis of NSCLCs using array comparative genomic hybridization. Cluster analysis using the 50 BAC clones closely correlated with histological subtype allowed accurate discrimination between SqCa and AdCa. K-nearest-neighbor classification was used to formally test the ability to predict subtype from array CGH profile. Cross-validation yielded 24/27 (89%) correct histological classification. Green squares: increase in copy number of a specific BAC clone, red squares: decrease in copy number.