Endogenous AQP4 relocalization in primary cortical astrocytes. Cell surface biotinylation of primary rat astrocytes subjected to hypotonic stress and analysis of endogenous AQP4 surface expression is shown, n = 3. As a negative control for translocation, membrane expression of the glutamate transporter EAAT1 was measured under the same hypotonic conditions, n = 3. All data are presented as mean ± S.E. p values and significance on the graph refer to AQP4. None of the variability in EAAT1 surface expression was statistically significant, p = 0.37. n.s., not significant.