To confirm the utility of the R26PR mouse model, we mated R26PR mice to the hematopoietic-specific Cre-recombinase-expressing line Tg(Mx1-cre)1Cgn/J (hereafter called Mx1-cre) to determine whether deletion of the FS cassette and subsequent expression of Prdm14 in R26PR animals would also result in leukemia. This evidence concerns the gene MX1 and leukemia.