MBP and myeloid sarcoma: Although the binding affinity between Fyn-SH3 and U24 from HHV-6A was found to be weaker than that between MBP and Fyn-SH3 [158], the suggestion that a number of viruses that potentiate each other may be collectively involved in MS, e.g., HHV-6A, HHV-6B, Epstein–Barr virus (EBV), Varicella Zoster Virus (VZV) [159], may provide the high concentration of PxxP motifs required to deplete Fyn.