AR and prostate cancer: In prostate cancer cells, V‐ATPase co‐localized with prostate specific antigen (PSA; a secreted tumor marker that is regulated by the androgen receptor [AR]) in the Golgi and V‐ATPase inhibition resulted in a relocalization of PSA to lysosome‐like intracellular vesicles.50 Interestingly, in androgen‐sensitive LNCaP prostate cancer cells, V‐ATPase inhibition also reduced PSA mRNA expression, suggesting upstream inhibition of AR's transcription activating activity.50