FIGURE 7.

Akt_i effect on NHE3 activity requires NHE3-Ser⁵¹⁵ even when NHE3-Ser⁵²⁶ is phosphorylated. PS120 (A) and OK (B) cells stably expressing WT NHE3, NHE3-S526D, and NHE3-S515A,S526D (called double mutant) were exposed to Akt_i. Although Akt_i inhibited NHE3 when Ser⁵²⁶ was mutated to Asp alone, the additional mutation of S515A prevented the Akt_i effect. The results are means ± S.E. of three separate studies. p values are comparisons of Akt_i effect compared with untreated control in the same cells.