Fig. 2. Pathogenesis of hemangioblastoma in VHL disease. A poorly understood stromal cell undergoes loss of the remaining wild-type VHL allele, leading to loss of pVHL function and consequent overproduction of mRNAs encoded by hypoxia-inducible genes. Some of these mRNAs encode angiogenic peptides, such as PDGF and VEGF, whereas others encode autocrine growth factors such as TGF-{alpha}.