The receptors for these ligands (NP1 and NP2) are expressed by OPCs in and around all types of MS lesions, as well as by astrocytes and microglia/macrophage, suggesting that it is the differential expression of Sema3A and 3F in different MS lesions which confers different OPC recruitment patterns and their subsequent capacity to remyelinate (Fig. 11). The gene discussed is SEMA3A; the disease is myeloid sarcoma.