Effect of cyclophilin B knockdown on NaDC1 expression and function. A, knockdown reduced total NaDC1 expression in NaDC1-transfected HEK293 cells by ∼85%. B, knockdown reduced citrate influx of NaDC1-transfected cells only. Inset, recombinant NaDC1 activity (black bars) and its CypB knockdown-sensitive fraction (dashed part; 40%). C, Western blot analysis showing the efficacy of CypB knockdown in HEK293 cells. Knockdown reduced CypB expression by ∼65%. Gray bars: CypB knockdown. Data were normalized to values obtained with NaDC1- and scrambled siRNA-transfected cells, expressed as %, and shown as averages (± S.E.) of 3–11 experiments. *, and **, significant difference to NaDC1- and scrambled siRNA-transfected cells (p < 0.05 and 0.001, respectively).