Generation of Tet2:nlacZ/nGFP knock-in mice and evaluation of the levels of GFP (Tet2) expression in different hematopoietic cell populations. (A) A nlacZ/nGFP-FRTNeoFRT cassette was introduced into 6bp upstream of Tet2 start codon (exon 3). (B) Southern blot of ES cell DNA digested with ScaI (S) and hybridized with a genomic fragment external to the 5′ arm displayed a wild-type (WT) band of 6.3 kb and a recombinant band of 4.0 kb, and ES cell DNA digested with EcoRI (E) and hybridized with a probe external to the 3′ arm displayed a WT band of 10.3 kb and a recombinant band of 8.9 kb. Square bars indicate exons. (C) BM cells from 6- to 8-week-old heterozygous Tet2:nGFP mice were separated into GFP^hi and GFP^lo/− cells and Tet2 expression levels were measured by quantitative real-time PCR. (D) GFP (Tet2) expression levels in various hematopoietic cell populations of BM cells from a representative 7-week-old heterozygous Tet2:GFP mice.