We established a cisplatin-resistant (CIS-R) and doxorubicin-resistant (DOX-R) MDA-MB-231 cell line derivatives, and found that, in addition to increased WAVE3 and CSC markers expression levels in the CIS-R and DOX-R cells, expression levels of β-catenin were also significantly increased, which was reflected in increased tumor burden in mice injected with the CIS-R cells, even after treatment with chemotherapy. This evidence concerns the gene WASF3 and neoplasm.