As mentioned above, Apo D is expressed mainly by mature OLGs as wells as OPCs in the brain which, in turn, are ultimately responsible for the restoration of new myelin sheaths in demyelinated axons in MS (Hu et al., 2001; Bradl and Lassmann, 2010; Clemente et al., 2013; de Castro et al., 2013). This evidence concerns the gene APOD and myeloid sarcoma.