Figure 7. Dose-dependent inhibition of CSC propagation using DPI, as measured using the mammosphere assay. MCF7 cells were seeded into low-attachment plates and allowed to form mammospheres (a.k.a., 3D tumor spheres), over a period of 5 days. Note that DPI markedly reduced CSC propagation, with an IC-50 of 3.23 nM. The mammosphere assay was performed over the range of 0.2 nM to 10 µM.