It has recently been shown that Atp6v1c1 (C1), an isoform of the v1c subunit, was the most strongly overexpressed V-ATPase subunit in metastatic oral squamous cell carcinoma suggesting that V-ATPase activity, and specifically ATP6v1c1, indeed facilitates tumor progression and metastasis [8, 13, 16, 17]. The gene discussed is ATP6V1C1; the disease is oral cavity squamous cell carcinoma.