CAPE stimulates the β-oxidation activities and lowers the levels of saturated and monounsaturated VLCFA in human X-ALD skin fibroblasts. Human skin fibroblasts from ALD (GM04932, GMo04934) and AMN (GM07530) patients were incubated in serum-containing DMEM with different concentrations of CAPE and lignoceric (A) and palmitic (B) acid β-oxidation activities were measured after 3 days as described in Materials and Methods. After every 24 h, medium was replaced with the addition of fresh reagents. FAME was prepared directly from cells as described in Material and Methods. FAs were analyzed by GC after adding C27:0 as an internal standard. C26.0, C26:1, and C22:0 were measured as a percent of total FAs and expressed as ratio of C26:0/C22:0 (C) and C26:1/C22:0 (D). Results represent the means ± SD of duplicates from three different experiments.*P<0.05; **P<0.01; ***P<0.001; NS, non- significant.