To examine the generality of these effects, we compared the effects of siRNA-mediated suppression of HIF-1α or HIF-2α on PHD3 expression in a wider selection of RCC and non-RCC cells, using the independent HIF isoform-specific siRNA duplexes described by Sowter et al (2003). The gene discussed is HIF1A; the disease is renal cell carcinoma.