However, the fact that astrocytes appear as the major or minor TNF-α expressing cell types in MS lesions might be because astrocytes internalize the protein in a receptor-mediated manner (Aránguez et al., 1995, Kuhlmann et al., 2006) rather than producing it themselves as suggested by Hofman et al. (1989) and Bitsch et al. (2000). The gene discussed is TNF; the disease is myeloid sarcoma.