Fig. 1

Morphology of BI-12 cells from different cell culture passages. A In cell culture passage 2 (P2) attached cells showed mixed epithelial/mesenchymal appearance and single round cells float in suspension or stick to adherent cells. B At passage 3 (P3) single cells attach to the extended patches of adherent epithelial cells and fibroblasts. Subsequently, the small cells overgrew the epithelial cells and fibroblasts disappeared. At passage 7 (P7) only small cells were visible forming loosely connected spheroids. C A colony of adherent cells in passage 5 imaged over the course of 32 days (D4 = Day 4, D20 = Day 20, and D32 = Day 32). Epithelial cells disappeared while loosely attached round cells expanded as spheroids. D Late passages of P27 and P30. E Growth curve of the obtained cells depending on MTS assay, the doubling-time was 34.33 ± 4.96 h based on 3 independent triplicate experiments (Suppl. Table S2). P1-P30 = passages 1–30; scale bars = 100 μm