Fig. 1

Induction of DR-BC cells from their corresponding parental DS-BC cells through continuous low-dose doxorubicin pressure in a step-wise manner. a-d CCK-8 assay was used to determine cell proliferation abilities. e, f Colony formation assay was conducted to examine the colony formation abilities in BC cells. g, h Trypan blue staining assay was employed to determine cell viability. i-k Cell apoptosis was examined by using the Annexin V-FITC/PI double staining method. Each experiment repeated at least 3 times, and *P < 0.05 was regarded as statistical significance