DNA encoding influenza virus hemagglutinin A- (HA-) tagged human hypoxia-inducible factor 2 alpha (HIF2alpha) with nucleotide substitutions leading to replacement of proline by alanine at amino acid positions 405 and 531 (P405A;P531A), preceded by a floxed neo-STOP cassette, was inserted into the targeted locus. The STOP sequence must be removed by Cre-mediated recombination to allow for expression of the mutated coding sequence. The amino acid substitutions prevent oxygen-dependent prolyl hydroxylation at a.a. position 405 or 531, which is required for binding by von Hippel-Lindau tumor suppressor (VHL). (J:144666)