Sodium–hydrogen exchanger 2, also called SLC9A2 or NHE2 is a protein that in humans is encoded by the SLC9A2 gene. This gene is mapped to 2q12.1. The Na+/H+ exchangers (NHE) are membrane proteins involved in cell volume. The exchanger (which they called NHE2) is found in several tissues, including intestine and kidney, and is highly expressed in villus and distal convoluted tubules. This gene is involved in pH regulation to eliminate acids generated by active metabolism or to counter adverse environmental conditions. It seems to play an important role in colonic sodium absorption.