RMCE on KH2 ES cells introduced into the 3' UTR a tetracycline-inducible CMV minimal promoter driving inducible expression of the human aminocarboxymuconate semialdehyde decarboxylase cDNA. The ES cells also contain the Gt(ROSA)26Sortm1(rtTA*M2)Jae allele. By treating this mouse line with doxycycline, rtTA*M2 binds the tetO promoter and human aminocarboxymuconate semialdehyde decarboxylase is expressed.