Figure 2. The effect of NPB304 on the paclitaxel sensitivity of resistant cells.

(A) Cytotoxicity of NPB304 in the two pairs of cell lines (MX-1, MX-1/paclitaxel; MCF-7 and MCF-7/paclitaxel). (B) NPB304 reduces the IC₅₀ of paclitaxel in resistant breast cancer cells. Resistant cells were treated with the indicated drugs for 72 h and subjected to an MTT assay. (C) The cells were treated with paclitaxel in the presence or absence of NPB304 for 12 days. Colony numbers were counted after Giemsa staining. *p<0.05, **p<0.01, Student's t-test (n = 3) or one-way ANOVA (n = 3).