Statistical analysis

The software IBM SPSS was used for all statistical analyses. The results were tested for homogeneity of variances each and as described elsewhere [32, 33], the normal distribution was neglected. For the cell viability assay, a one-way ANOVA was performed following the Dunnett-T post-hoc test in case of homogeneity of variances or the Dunnett-T3 if this was not the case. Statistical differences of the type-III foci in the BALB-TTM and the glucose concentration in the medium were calculated for existing homogeneity of variances with a one-way ANOVA and an additional Bonferroni post-hoc test. Otherwise, a Dunnett-T3 post-hoc test was performed.

Positive or negative drug combination effects were further described with the Highest Single Agent approach [34]. According to that, the Combination Index (CI) was calculated as following, with max(E_A,E_B) describing the effect of the highest concentration of the single agent and E_AB for the effect for the combination treatment:

Hence, the CI gives information whether the combination of two components shows greater (CI > 1) or smaller effects (CI < 1) compared to a single agent alone.