SOX2 is highly expressed in chemoresistant cells. (A) Viability measured after 48-h exposure to a range of concentrations of carboplatin compared to vehicle control for 2-D conditions and 3-D conditions, Two-way ANOVA treated vs vehicle. (B) IC50 calculations for carboplatin in 2-D and 3-D conditions, calculated with Least Squares Fit. C–E) Cells treated with carboplatin for 72 h at IC30 were subjected to qRT-PCR to measure expression relative to vehicle control of (C) SOX2 (D) OCT4 and (E) NANOG, Student’s T-test treated vs vehicle. (F) qRT-PCR of SOX2, OCT4 and NANOG genes after sequential carboplatin treatments relative to pre-treatment, Students T-test treated vs pre-treatment. Data represent mean and SEM. * p < 0.05.