RR blocks AQP5 reduction in response with absolute or relative hypotonicity. MLE cells were incubated in medium for 30 min in the presence or absence of RR, and cell lysates were probed for actin and AQP5. Lanes are as follows: 1, 276 mosM; 2, 476 mosM, 8 h; 3, 476 mosM, 8 h, then 127 mosM, 0.5 h; 4, 476 mosM, 8 h, then 127 mosM, 0.5 h plus RR (20 μM); 5, 476 mosM, 8 h, then 276 mosM, 0.5 h; 6, 476 mosM, 8 h, then 276 mosM, 0.5 h plus RR (20 μM).