Fig. 2. Stimulation of Edar expression (dl) in hair placodes by activin A but not by other signals. (A,B) Edar expression is stimulated by an activin A-releasing bead in placodes throughout the whole skin explant. (C) Activin A does not induce Edar expression in isolated skin epithelium. (D-I) None of the other tested signal proteins [BMP4, EGF, FGF10, SHH and WNT6 (introduced by cell aggregates)] or BSA control beads stimulated Edar expression. (J-L) Positive controls: (J) Msx2 expression induced by BMP4. (K) Ptch (Ptc) induced by SHH. (L) Lef1 induced by WNT6-expressing cells. Scale bar: 200 µm.