To this end, immunofluorescence experiments were first performed on cells transfected with AQP4-M1 TIS having a pyrimidine (C−3 or T−3) or a purine (A−3 or G−3), using commercial AQP4 antibody and NMO sera, to measure, surface expression (by TIRF microscopy) and NMO-IgG binding, respectively. Here, AQP4 is linked to neuromyelitis optica.