Global mRNA profile analysis of Pre-PCs and PCs. (A) Hierarchical clustering of all 9 Pre-PC and PC pairs. (B) Hierarchical clustering of the 1000 more differentially expressed genes in 7 pairs of Pre-PCs and PCs. (C) Principal component analysis on 1509 differentially expressed genes (P < .05) in which PCs and Pre-PCs were clearly separated along the first principal component in all 7 pairs. (D) Pathway analysis of genes involved in separating PCs and Pre-PCs. The 3 top scoring gene clusters are enriched in Pre-PCs and contain genes involved in chromatin modification, chromatin organization, and chromosome organization. P values represent a Benjamini-Hochberg corrected modified Fisher exact test.