Validation of a narrow selection of transcripts as a tool for clustering responders versus non-responders. Ten responders (R) and ten non-responders (NR) were included in two validation subsets (subset 2 in text and Tables 2 and 3). In any given sample of peripheral blood mononuclear cells, the abundances of informative transcripts were determined by qRT-PCR and normalized with the corresponding 18S RNA level. Unsupervised hierarchical clusterings obtained with (a) 20 or (b) 8 selected transcripts are shown. Expression of transcript levels and scale bar are as in Figure 1.