Figure 4: Correlation of the QC matrix with SAGE libraries from uncharacterised or cancer libraries. Pearson correlation coefficients (vertical axes) calculated between individual SAGE libraries and the EST-derived QC expression matrix. The selected examples illustrate uncharacterised, incorrectly defined or cancer libraries indicated by their correlations which contradict libraries’ annotations. A: uncharacterised or ill-defined preparations (left to right): peritoneum library SAGE_Peritoneum_normal_B_13 (expected match: liver, gastrointestinal tract and colon), white blood cell library SAGE_Leukocytes_normal_B_1 (expected match: vascular), “SAGE_Esophagus_Normal_B_CN01” library (expected match: gastrointestinal tract) and “SAGE_GallBladder_Normal_B_HN” expression library (expected match: liver). B: cancer libraries (left to right): brain cancer library “SAGE_Brain_medulloblastoma_B_98-05-P608”, brain library “SAGE_Brain_ glioblastoma_B_H1110”, brain cancer library “SAGE_Brain_astrocytoma_grade_I_B_H1043”and brain cancer library “SAGE_Brain_astrocytoma_grade_III_B_ H1020”.