Immunofluorescence images of the differentiated cells.

<p>Expression of ABCG2, p63, and CK14 at day 6 and CK3 at day 12 of differentiation in the cells cultured under 5% CO<sub>2</sub> (A), 7% CO<sub>2</sub> (B), and 9% CO<sub>2</sub> (C). Scale bar, 20 μm.</p>