Fig. 3. GDNF signaling in wild-type and myr-Akt-Mer GS cells. (A) Phosphorylation of Akt and Gsk3ß in wild-type GS cells. GS cells on laminin were starved for 4 days, and then left untreated or treated with GDNF. Where indicated, cells were also incubated for 45 minutes with 33 µM LY294002 before the addition of GDNF. (B) Phosphorylation of Akt and Gsk3ß in myr-Akt-Mer GS cells. The myr-Akt-Mer GS cells on laminin were cultured with GDNF or indicated concentrations of 4OHT for 6 days. White and black arrowheads represent endogenous Akt and myr-Akt-Mer, respectively. (C) Phosphorylation of MAPK after GDNF or 1 µM 4OHT stimulation. (D) Expression of cyclin molecules after GDNF or 1 µM 4OHT stimulation.