SLC9A1 and neoplasm: NHE1 is crucial to accelerate migratory velocity and to maintain directed migration in fibroblasts, immune cells, and tumour cells, but this is in part due to NHE1‐dependent protein–protein interactions rather than NHE1‐mediated ion transport (Denker & Barber, 2002; Stock et al., 2008, 2005).