Figure 6. Semiquantitative reverse transcriptase (RT)-PCR analysis. The expression of the stem cell markers ATP-binding cassette transporter G2 (ABCG2), cell surface antigen Sca-1, p75 neurotrophin receptor (p75NTR), β-1 integrin, B-cell lymphoma 2 (Bcl2), and nestin in SP and non-SP cells was analyzed by semiquantitative RT-PCR. Open bars indicate mRNA levels in non-SP cells; gray bars indicate mRNA levels in SP cells. SP cells express more ABCG2 than non-SP cell. All stem cell markers were expressed at higher levels in SP cells than non-SP cells. Stem cell antigen 1 was expressed at 26 fold higher levels in SP cells than in non-SP cells.