Grouping of key gene changes between NODk and B10k thymocytes. Analysis of Affymetrix GeneChip data segregated those probesets that were significantly modified in a 2 × 2 × 2 F-test (p < 0.005) into groups 1 to 6 based on logical sets of significant contrasts (p < 0.05). The diagrams show relative changes for the mean gene expression in the pre-selection (PreS), positive selection (S+) and negative selection (S-) conditions. The number of probesets falling into each group is listed on the group pattern. B10k expression changes are shown in red, NODk expression changes are shown in blue.