Figure 3E. Copyright: Reprinted with permission from Elsevier from [doi:10.1016/S0925-4773(01)00412-9] Mech Dev 106: 155-8, Becker MB; Zulch A; Bosse A; Gruss P, "Irx1 and Irx2 expression in early lung development." Copyright 2001. [PMID:11472847]