Fig. 2. Copper is required for HCT-13 activity. (a) Intracellular concentrations of copper measured by inductively coupled plasma mass spectrometry (ICP-MS) in MIAPACA2 PDAC cells treated with HCT-13 (25 nM) for 24 h ± Cu(ii) (20 μM); *** P < 0.001; V: vehicle. (b) Viability of MIAPACA2 cells treated with HCT-13 (25 nM) + Cu(ii) (20 μM) for 24 h ± bathocuproine disulfonate (BCPS, 300 μM) measured by trypan blue exclusion; * P < 0.05; ** P < 0.01; V: vehicle, NS: no supplement. (c) Proliferation rate of MIAPACA2 PDAC cells measured by CellTiterGlo following HCT-13 treatment for 72 h ± Cu(ii), Fe(ii) or Zn(ii) (20 μM). (mean ± SD, n = 2, one-way ANOVA corrected for multiple comparisons by Bonferroni adjustment).