Generation and bioluminescent imaging of MMTV-Luc2 mice. (A) Schematic of the transgenic construct used for generation of MMTV-Luc2 mice. (B)Whole-body luminescent imaging of representative nulliparous F1 females from sub-strains obtained by crosses of F0 female founders with wild-type FVB/N males. MMTV-Luc2 sub-strain #3 (arrow) was selected for further studies. Wild-type: FVB/N female; 1, 3, 4, 5: numbers of the respective sub-strains (please refer to Additional file 1 Figure S1). [Note: strain #2 was discontinued prior to imaging because of indication of embryonic lethality during transgene vertical transmission studies].