sentences:  Tumors develop in mice injected with "FLCN"-deficient kidney cancer cells from BHD-associated human tumors but when wild type "FLCN" is restored in these cells, tumor development is inhibited.Additionally, injection of kidney tumor cells from the adenocarcinoma cell line ACHN with "FLCN" inactivation into immunocompromised mice resulted in the growth of significantly larger tumors, further underscoring a tumor suppressor role for FLCN.Based on the presence of FLCN staining by immunohistochemistry, haploinsufficiency, that is mutation of one copy of "FLCN" with retention of the wild type copy, may be sufficient for the development of fibrofolliculomas  and lung cysts.