The Na+/H+ exchanger NHE1 (SLC9A1) accumulates at the leading edge of migrating fibroblasts (human and hamster lung [48]; murine embryonic [95]), renal epithelial cells (canine [72]), and melanoma cells (human MV3 [157] and murine B16V cells [95]). The gene discussed is SLC9A1; the disease is melanoma.