Validation of the PGC in Independent Data Sets.

aNumber of genes in the original PGC signatures (e.g., PGC = 48 genes). bNumber of PGC signature genes that are tightly regulated in the test sets (CV<0.28). cTotal number of tightly regulated genes in the test sets (CV<0.28). dStatistical significance of PGC signature enrichment, calculated by the hypergeometric distribution test. P-values with significance (<0.01) are highlighted in bold. eNumber of samples in the test data sets.