A construct containing the Fos (FBJ osteosarcoma oncogene, minimal promoter) driving the tetracycline regulated transactivator (tTA) sequence, the SV40 polyadenylation signal sequence and a second construct containing a two hour half-life Green Fluorescent Protein (shEGFP) under the control of the Fos minimal promoter, were co-injected into fertilized B6D2F2 mouse eggs. These co-injected transgenes segregate as a single transgene. (J:125221)