Fig. 5.

THZ1 in combination with lapatinib enhances cell death in HER2iR BC cells. a Combination index (CI) plots. Fraction affected refers to the proportion of cells with inhibition of viability. Dose-response curves of lapatinib combined with THZ1 were determined for each cell line. CI values were calculated using the median-effect equation described by the Chou–Talalay method. CI < 1 indicates synergism, CI = 1 indicates an additive effect, and CI > 1 indicates antagonism. b, c Effect of lapatinib and THZ1 on clonogenic potential. After treatment of breast cancer cells up to 2 weeks, colonies were stained with crystal violet and the number of colonies was quantified. Data represent mean ± SD of three replicates. ****p < 0.0001 (one-way ANOVA). d HCC1569, HCC1954, and MDAMB453 cells were treated with vehicle control (DMSO), THZ1 (100 nM) and lapatinib (1 μM) alone or in combination for 24 h before immunoblotting using the indicated antibodies