To ensure that the GAP activity of FLCN is not due to co-purification of other mammalian proteins, we GST-purified FLCN WT protein, or a tumour-associated mutant form of FLCN (FLCN C9) from bacteria and tested their ability to hydrolyse GTP when combined with Rab7A. The gene discussed is FLCN; the disease is neoplasm.