A construct consisting of a splice acceptor site, floxed neo-stop cassette, hyperactivatable Nfatc2 gene, and an frt flanked IRES-GFP cassette was inserted into intron 1 via homologous recombination. The hyperactivatable Nfatc2 gene contains mutations in the calcineurin docking site resulting in higher affinity for ligand. The mutant protein sequence is HPVIVITGP. (J:148341)