Figure 2

PCA on expression data of all 4,978 samples that passed expression quality control. (a) The first two expression components show clear separation between primary tissue samples in green, cell lines (HeLa, K562, Hep G2, and so on) in blue and hematologic tissues and cell types in different shades of red and yellow. (b-d) The two best discriminating components for the different primary tissues. Each letter represents a sample from a distinct study showing that this clustering is not driven by a study-specific effect. For each of these three primary tissues, we show an example eQTL effect specific to these tissues. LCL, lymphoblastoid cell line; PBMC, peripheral blood mononuclear cell.