Fig. 3. ATP--S activates EGFR signaling in corneal and airway epithelial cells. (A-C) Growth-factor-starved THCE cells (A), primary HCE cells (B) or serum-starved BEAS 2B cells (C) were stimulated with 100 µM ATP--S for the indicated times. Cells were then lysed. THCE cell lysates were immunoprecipitated with EGFR antibody, immunoblotted with anti-PY99 antibody (P-EGFR) and re-probed with anti-EGFR antibody (EGFR) to assess the amount of EGFR precipitated. Lysates of THCE, primary HCE and BEAS 2B cells were also subjected to western blotting with antibodies against phosphorylated AKT (P-AKT), phosphorylated ERK1/2 (P-ERK), EGFR Y1068, AKT and ERK2.