Fig. 2. Characterization of Ngn3-Nkx6.1 and Pdx1-Nkx6.1 transgenic mice. (A) The Ngn3-Nkx6.1 transgenic construct comprises the Ngn3 promoter fused to Nkx6.1 cDNA followed by an IRES-eGFP-polyA cassette. (B) In Ngn3-Nkx6.1 embryos at E14.5, 60% of the transgene-expressing;GFP⁺ cells express Ngn3 (arrows). (C,D) Whereas 26% of Ngn3⁺ cells are co-positive for Nkx6.1 in wild-type embryos at E16.5 (C, arrows), this percentage is increased to 61% in Ngn3-Nkx6.1 embryos (D, arrows). (E) In the Pdx1-Nkx6.1 transgenic construct, the Pdx1 promoter drives the expression of Nkx6.1 cDNA and an IRES-lacZ-polyA cassette. (F-I) lacZ expression in Pdx1-Nkx6.1 mice is detected in the ventral (vb) and dorsal (db) pancreatic anlagen at E10.5 (F), in the entire pancreatic epithelium at E14.5 (G), and in a subset of pancreatic cells at E18.5 (H) and postnatal day (P)6 (I). (J-L) ß-galactosidase (ß-gal) and Pdx1 are co-expressed in pancreata from Pdx1-Nkx6.1 mice at E14.5 (J, ß-gal in green; K, Pdx1 in red; L, merged). However, some Pdx1⁺ cells are negative for the ß-gal reporter (L, arrows). db/vb, dorsal/ventral pancreatic anlagen. Scale bars: 50 µm in B for B-D and in J for J-L.