On the other hand, one of the recombinant monoclonal NMO-IgGs, rAb-53 induced little endocytosis of endogenous mouse AQP4 (mAQP4) in primary cultured astrocytes [15], [21], [23], despite the fact that it did endocytosis of ectopically expressed AQP4 in a stable cell line [21]. The gene discussed is AQP4; the disease is neuromyelitis optica.