Intracellular pH regulation by Na+/H+ exchanger-1 (NHE1) is required for growth factor-induced mammary branching morphogenesis

► Mammary tissue undergoes branching morphogenesis in response to TGFα stimulation ► TGFα activates mammary associated NHE1 exchanger activity through PI3K. ► NHE1 activation by TGFα induces rapid intracellular alkalization. ► Inhibiting NHE1 activity and alkalization leads to increased MAPK activation. ► Inhibiting NHE1 during TGFα stimulation leads to abnormal mammary development.