Fig. 6

Lapatinib inhibits the stemness of erbB-2-overexpressing breast cancer in vitro. BT474 (a) and 78617 (b) cells were cultured in vitro and subjected to primary and secondary tumorsphere assays. In the primary tumorsphere assay, cells were initially treated with lapatinib (0, 0.1, or 0.3 μM) for 6 days for primary sphere formation. Then primary tumorspheres were harvested and replated for another 6 days under identical incubation conditions to form secondary spheres. Primary and secondary tumorsphere formations were recorded. Values are presented as the means ± S.E. (** p < 0.01 as compared to the corresponding untreated control samples). Representative images from each assay are depicted in the right panels. c SKBR3 and 78617 cells were treated with lapatinib (0, 1, or 3 μM) for 40 h, followed by quantification of ALDH-positive cells. The percentage of ALDH-positive cells was determined using the ALDEFLUOR detection kit with flow cytometry. Values are presented as the means ± S.E. (* p < 0.05; ** p < 0.01 as compared to the control for each cell line)