In a study utilising mice with superoxide dismutase 1 (SOD1) G93A mutation (SOD1G93A), the expression of AQP4 in the spinal cord was increased together with disease progression, but this was coupled with a reduction of AQP4 polarity within the end-feet of astrocytes in the spinal ventral horn in SOD1G93A mice, in both early and late stages of ALS, with further analysis identifying down-regulation glutamate transporter-1 (GLT-1) in the end-stage SOD1G93A mice [91]. Here, AQP4 is linked to amyotrophic lateral sclerosis.