Fig3A.Copyright: Reprinted with permission from Elsevier from [doi:10.1016/S0925-4773(99)00203-8] Mech Dev 89: 65-74, Folberg A; Kovacs EN; Huang H; Houle M; Lohnes D; Featherstone MS, Hoxd4 and rarg interact synergistically in the specification of the cervical vertebrae Copyright 1999.