The bacterial artificial chromosome (BAC) RP23-224O8, modified by GENSAT to insert the coding sequence for enhanced green fluorescent protein (EGFP) downstream of the 5' regulatory sequences of the mouse NK2 homeobox 2 gene (Nkx2.2), was obtained from CHORI and microinjected into the male pronuclei of fertilized oocytes. Founder line 2 exhibited the strongest EGFP expression. (J:214964)