In a cuprizone-exposure model of MS, cuprizone induced severe demyelinating injury as detected by reduced myelin immunolabeling and suppressed critical peroxisome transcripts, including Abcd1, Cat (catalase), and Pex5L, which was prevented by treating cuprizone-exposed mice with the peroxisome proliferating agent, 4-PBA. The gene discussed is ABCD1; the disease is myeloid sarcoma.