Characterization of sphere cells derived from the primary tumor and the patterns of gene expression. (a) Sph cells (sphere culture) and Ser cells (serum culture) were cultured in suspension for 1 week and then transferred to attachment conditions. (b) Tumor growth in mice injected with Sph cells and Ser cells. Data are shown as the means ± SD. All statistical analyses for data in this figure were performed using a paired Student’s t-test. (c) Tumorigenicity of Sph cells at the subcutaneous injection site. Sph cells and Ser cells were injected into NOD/SCID mice at 1 × 102 cells/mouse. (d) t-SNE map representation of transcriptome similarities between individual Sph cells and Ser cells. Red dots show cells positive for the indicated gene. (e) Immunohistostaining for SOX2 positive cells in the E-side and the M-side. Original magnification 100x for the insert in the upper left corner and 40x for the remaining area. (f) Percentage of SOX2 positive cells among three types of cancer cells in the E-side and the M-side.