Figure 2.

Drug-selected melanoma cells persisted the characteristics of melanoma-stem like cells. (A) cell sphere forming assay under suspension culture for 2 weeks. Cell spheres were formed by drug-selected cells, while parental cells formed mostly cell aggregates. Spherocrit assay showed longer sphere length in capillary tube by cell spheres from drug-selected cells. (B) Quantification of sphere lengths from drug-selected cells through different selection cycles. (C) Side population analysis of parental and drug-selected cells showed more percentage of side population cells as determined by low dual fluorescence of hoechst33342-red and hoechst33342-blue. (D) Animal experiments of subcutaneous tumor formation showed larger tumors derived from drug-selected cells.