Figure 1

Catalase immunofluorescence of fibroblasts incubated with arginine. PEX1-G843D patient fibroblasts were incubated for 7, 14 or 21 days with different concentrations of arginine, glycerol or glutamine. Glycerol was used as a positive control. In four independent experiments, two cover slips per condition were examined for the number of cells with catalase-containing peroxisomes among at least 200 cells. Data are presented as means±SD, statistical analysis was performed with a two-tailed Student’s t-test, *, P < 0.05; **, P < 0.005; ***, P < 0.0005; ****, P < 0.0001 versus untreated PEX1-G843D fibroblasts. Two additional PEX1-G843D cell lines showed similar results (Additional file 1: Figure S1 and Figure 4). Control (C) showed 100% peroxisome-positive cells. PEX1-I700fsX41 (negative control = ZS) displayed no peroxisome-positive cells.