Fig. 2. Activation of Erk/MAPK and Akt/PI3K pathways mediates FGF-induced hairy2 expression.

(Ai) Immunoblots for Erk, p-Erk, Akt, p-Akt and β-tubulin (loading control) using total protein extracts from posterior or anterior FGF8-bead implanted limb halves and their contralateral controls, as schematically represented, after 4.5 hours of incubation. (Aii) Relative levels of Erk and p-Erk in the posterior and anterior control limb regions. (Aiii) Quantification of the fold change levels obtained in FGF-treated tissues relative to the posterior control. FGF8 significantly increases both p-Erk and p-Akt levels. (B) Inhibition of FGF8-induced hairy2 expression by U0126 and LY4002 (MAPK and PI3K inhibitors, respectively). Arrowheads depict inhibition sites and delimited square areas in a,b,c are amplified in a′,b′,c′. Dorsal view; anterior to the top. *Beads, delimited by dashed lines.