The construct contained a cre recombinase cassette and bovine poly(A) sequence inserted in-frame downstream of the Hoxb8 ATG site. Fertilized early-stage C57BL/6 x DBA/2 oocytes were injected with the linearized construct, and four founders were obtained. Founders were mated to generated transgenic lines, two of which (1403 and 1404) exhibited the expected expression pattern on a gross scale at E9.5 and E11.5. Line 1403 carries a single copy of the transgene and was characterized in detail.