VHL and nonpapillary renal cell carcinoma: The current study was designed to a) investigate the incidence of PHD2/3, HIF-α in selected human solid cancers b) test the hypothesis that degradation of HIF-α by MSC is PHD2 and proteasome dependent, VHL and PHD3 independent and c) determine if these effects will translate into therapeutic benefit without toxicity in ccRCC tumor xenografts.