AQP4 and nervous system disorder: The potential involvement of AQP4 in common neurological disorders and the discovery of AQP4‐dependent fluid and waste clearance (“glymphatic”) pathways (Haj‐Yasein et al., 2011; Iliff et al., 2012) have created regained interest in AQP4's distribution and function (Hladky & Barrand, 2014; Nagelhus & Ottersen, 2013; Papadopoulos & Verkman, 2013; Smith, Jin, & Verkman, 2015; Spector, Robert, & Johanson, 2015; Thrane, Rangroo, & Nedergaard, 2014; Thrane, Rangroo, Plog, & Nedergaard, 2015).