Fig. 5. sHB-EGF activates EGFR-ERK signaling but not JNK signaling in the extending leading edge. (A,B) lacZ expression at the tip of the leading edge of HB^del/+ (A) and HB^del/del (B) eyelids. (C,D) Detection of sHB-EGF protein in the leading edge of HB^del/+ (C) and HB^del/del (D) eyelids. (E,F) High-magnification views of boxed areas in C and D. (G-N) State of activation of EGFR and downstream signaling molecules in the leading edge of HB^del/+ (G,I,K,M) and HB^del/del (H,J,L,N) eyelids. (G,H) Phosphorylated EGFR. (I,J) Total EGFR protein. (K,L) Phosphorylated ERK. (M,N) Phosphorylated JNK. Scale bars: 100 µm for A-D,G-N; 20 µm for E,F.