Effects of morpholino knock-down of Abcb4 or Abcb5 and of transporter inhibitors on accumulation of bodipy-vinblastine and vinblastine-caused mortalities in zebrafish embryos. A) Fluorescence micrographs depicting 48 hpf zebrafish embryos that had been incubated with bodipy-vinblastine either in combination with the inhibitor compound cyclosporin A (CsA) or upon knock-down of Abcb4 (Abcb4-SP-MO). The control was treated with dye only (ctrl), the morpholino control (ctrl-MO) served to exclude unspecific morpholino effects on dye accumulation in the embryos. B) Mortalities of zebrafish embryos upon treatment with morpholino nucleotides for knock-down of Abcb4 (Abcb4-SP-MO/Abcb4-ATG-MO) or Abcb5 (Abcb5-SP-MO) that were not exposed to any chemical (no vinblastine) or exposed to 2 μM vinblastine alone or in combination with 5 μM cyclosporin A (CsA) or 5 μM PSC833. Values are means +/− standard deviations from three to five independent experiments. The control morpholino (ctrl-MO)/2 μM vinblastine treatment served as reference for determining whether changes in mortality caused by 2 μM vinblastine were statistically significant when Abcb4 or Abcb5 were knocked-down or Abcb4 or Abcb5 knock-down was combined with CsA or PSC833 treatments. Significant differences were identified using one-way analysis of variance (ANOVA), followed by Dunnett’s test and are indicated by asterisks (P <0.05).