A monocarboxylic acid the structure of which is that of butyric acid substituted with a phenyl group at C-4. It is a histone deacetylase inhibitor that displays anticancer activity. It inhibits cell proliferation, invasion and migration and induces apoptosis in glioma cells. It also inhibits protein isoprenylation, depletes plasma glutamine, increases production of foetal haemoglobin through transcriptional activation of the gamma-globin gene and affects hPPARgamma activation.