AQP1 and Schnyder corneal dystrophy: The probability of AQP1 channel opening is low, modulated by tyrosine phosphorylation state, and the kinetics of channel gating are slow (Anthony et al., 2000; Campbell et al., 2012), consistent with a low amplitude background current that might escape detection in normal cells and account for the stochastic nature of Psickle in hypoxic SCD cells.