Figure 4.

Effect of cisplatin treatment on ALDH activity and sphere-forming efficiency. Cells in 10 cm dishes were treated with the previously determined IC₅₀ of cisplatin for ALDH-sorted fractions of the MPM cell lines. After the 48- and 72-h cisplatin treatments of ALDH^high- and ALDH^low-sorted cells, ALDH activity (A-C) was determined on surviving cells and compared with the non-treated cells to evaluate the effect of cisplatin by flow cytometry. The sphere-forming efficiency of the cisplatin-resistant cells was also evaluated as described in the Methods, and compared with the non-treated cells (D-F). Results represent the means and SDs of 3 independent experiments each. Data are statistically significant if p <0.05 (*p <0.05, **p <0.01, ***p <0.001). Representative images of spheres from non-treated and cisplatin-treated H2052 ALDH^high - and H2052 ALDH^low -sorted cells (G).