Principal component analysis of cell lines with 12 genes based on qPCR data. PCA differentiates four histopathological subtypes by three-dimensional expression clustering. The values of triplicate qPCR assays for each sample were analyzed. Results of PCA are shown in the three-dimensional contribution scores for component numbers 1, 2, and 3 (PC1, PC2, and PC3), which discriminate the four histopathological clusters. Data are shown for the eight test cell lines alone (A) and in combination with the four validation cell lines (B). The contribution scores were produced by conversion from each eigenvector value.