Screening for chemicals or downregulated genes synthetic lethal with VHL inactivation was made possible by the observation by Kaelin's group that unlike most human tumour suppressor genes ectopic expression of VHL does not lead to inhibition of cell growth or of cell-cycle distribution in vitro, but rather to suppressing tumour formation in nude mice xenografts (Iliopoulos et al, 1995). The gene discussed is VHL; the disease is neoplasm.