FH and cystic kidney disease: In favor of the pseudo-hypoxic mechanism, other studies in Fh mutant mouse embryo fibroblasts (MEFs) derived from Fh1-deficient mice show up-regulation of Hif1α protein as well as some of its target genes [Hk2, Glut1, and LdhA (11)] mimicking what was observed in murine renal cysts.