VHL and neoplasm: Secondly, heterozygous deletion of the mouse homologue of the VHL gene, Vhl (previously referred to as Vhlh), in the entire mouse (Haase et al, 2001), or homozygous deletion under the control of kidney-specific Cre transgenes, does not lead to proliferative dysregulation or tumour formation in the kidney (Frew et al, 2008b; Rankin et al, 2006).