AQP5 and dry eye syndrome: However, contrary to the notion of using demethylating drugs to restore salivary function, a more current study confirmed that AQP5 is not repressed but overexpressed in SGEC of SS patients, and it was shown that anti-muscarinic type 3 receptor (α-M3R) suppresses AQP5 trafficking to the membrane which contributes to the keratoconjunctivitis sicca in SS patients (Lee et al., 2013).