A vector was generated in which the cre recombinase sequence is driven by the 1.8 kb promoter of Lcn5. Male C57BL/6 pronuclei of fertilized oocytes were microinjected with the linearized vector. 11 founders were identified by PCR, but only 1 line exhibited cre recombinase expression specifically in the caput epididymis. (J:194481)