Figure 4

Sphere formation in serum-free medium. Tumor Cells formed nonadherent spheres in serum-free medium. The percentage of p75^NTR+ cells increased to 68.3% in Eca109, 62.7% in SHEC-1, 58.5% in SHEC-4 and 74.2% in SHEC-5 (A). Single p75^NTR+ cell could proliferate in serum-free culture and formed nonadherent cells sphere (B), contained both p75^NTR+ and p75^NTR- cells (C); p75^NTR+cells obtained from the spheres did not expressed differentiated markers involucrin (D) and cytokeratin 13 (E). Floating p75^NTR+cells could adhere and expressed involucrin (F) and cytokeratin 13 (G) in DMEM containing 10% fetal bovine serum. In addition, p75^NTR+ cells could be expanded as floating cell spheres for more than 30 passages, and the percentage of p75^NTR+ cells from passage 10, passage 20 and passage 30 was 66.4%, 56.3% and 59.2%, respectively (H). B and H bars = 100 μm. (F and G, bars = 50 μm)