mRNA levels of both PAG1 and the well-known hypoxia-inducible CAIX were robustly upregulated by 3- to 11-fold in all cancer cell lines examined, except in VHL-deficient 786–0 ccRCC in which PAG1 levels were constitutively high (Figure 1A). This evidence concerns the gene VHL and nonpapillary renal cell carcinoma.