PTGER4 and myeloid sarcoma: We previously reported that PGE2 synthesis and PGE2 receptor (EP1, EP2, EP4) expression were elevated in acute MOG-EAE lesions42, and that both EAE mouse spinal cord and MS brain lesions exhibited dominant expression of microsomal PGE2 synthase 1 (mPGES-1) in macrophages42.