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 This evidence concerns the gene KLK3 and neoplasm.