Figure 2

Growth factor gene expression by differentiating embryoid bodies. Polymerase chain reaction analysis indicated that the gene expression of several growth factors increased over time during embryonic stem cell (ESC) differentiation within embryoid bodies (EBs) (A, B, C) while others decreased relative to ESCs during early differentiation and then increased as differentiation progressed (D, E, F). The relative values of expression are reported as the relative fold-changes by EBs compared with the starting population of undifferentiated ESCs. Results indicate the mean ± standard error (n = 6). Analysis of variance: *P < 0.05, #P < 0.001, and †P < 0.05 compared with ESCs. BMP-4, bone morphogenic protein; FGF-2, fibroblast growth factor-2; IGF, insulin-like growth factor; PDGF-B, platelet-derived growth factor-B; VEGF-A, vascular endothelial growth factor-A.