A CAG-Loxp-PGK-Neo-poly(A)-Loxp-Runx1 cassette was inserted into the Rosa26 locus. The cDNA containing a complete open reading frame of Runx1 was inserted after the second Loxp site. Constitutive Runx1 expression is observed upon removal of the STOP cassette by Cre-mediated recombination. (J:242690)