Fig. 4. Cell viability data obtained from ATP assay. Data points are means ± standard error of 3 ± 1 independent experiments which each were conducted in 4 replicates. * indicates significant difference at 0.01 level. p < α = 0.01 (ANOVA one-way). Inset table shows half-maximal inhibitory concentrations (IC50) in μg ml–1. 2D cell culture having a biphasic dose–response curve possesses two IC50 values (IC50-1 and IC50-2) whereas each 3D spheroid cultures have one IC50 value owing to monotonic dose–response pattern. Acceptance criteria is CV (coefficient of variance) < 20%.
