Figure 2. Treatment conditions can be distinguished based on changes in global gene expression using principal component analysis (PCA). A: Principal components were calculated for each the three treatments (red=ciliary neurotrophic factor [CNTF), green=fetal bovine serum [FBS], blue=standard medium [SM]). Data from each of these treatments shows considerable separation from the other two, with CNTF and SM at the two extremes. B: A Venn Diagram showing significant genes (|fold change|>2, false discovery rate [FDR] α<0.05) unique to either CNTF or FBS treatments (normalized to SM), as well as those genes significantly expressed in both treatments. The top number in each piece is the total gene count in that area, and the numbers below indicate the number of those genes that are upregulated and downregulated.