Additional file 2: of A novel spheroid-based co-culture model mimics loss of keratinocyte differentiation, melanoma cell invasion, and drug-induced selection of ABCB5-expressing cells

Figure S2. Comparison of SK-MEL-28 response to docetaxel in 2D versus 3D. 2D cultures of SK-MEL-28 cells were grown up to 50% of confluency. Tri-culture spheroids were produced by 3D cultivation of fibroblasts for 3 days, followed by the combined addition of keratinocytes and melanoma cells, and another 2 days without treatment. Then, all cultures were treated with different concentrations of docetaxel for 24 h (2D) or 48 h (spheroids). Spheroids were cryosectioned into 10-μm-thick slices, 2D cultures were directly fixed. Subsequently, all samples were labeled with Dapi and then imaged by confocal microscopy. The numbers of remaining SK-MEL-28 cells (2D cultures) or of external SK-MEL-28 cells (spheroids) were determined. The graph shows the amounts of SK-MEL-28 cells as a function of docetaxel concentration and normalized to the control condition without docetaxel. Given is mean ± SEM (n ≥ 3; * P