Figure 3. Expression of markers of epithelial stem cells and differentiation. RT-PCR analysis of expression of markers for epithelial differentiation (A) and stem cells (B) is shown. GAPDH was used as the normalizing control. The RT-PCR results of cytokeratin K5 and connexin 43 show a composite picture of PCR of cDNA from all three cells and the negative control that were performed in the same experiment. All experiments were performed twice with RNA isolated from a separate set of cultures.