SLC12A2 and Alzheimer disease: Up-regulated NKCC1 in AD may also help to counter cell shrinkage in the CP (Gosmanov et al., 2003; Johanson et al., 2004), while a rise in CSF K+ concentration resulting from neuronal damage could be buffered by the NKCC1 (Keep et al., 1994) and Na+ pump in the CP (Johanson et al., 1974).