Fig. 4. ATP--S-induced AKT and ERK phosphorylation is Ca²⁺ and EGFR dependent. Growth-factor-starved THCE cells were pretreated with either 50 µM Ca²⁺ chelator BAPTA-AM (A) or 1 µM EGFR inhibitor AG 1478 (B) for 1 hour and then stimulated with 100 µM ATP--S for 30 minutes. Cell lysates were subjected to western blotting with antibodies against phosphorylated AKT (P-AKT), phosphorylated ERK1/2 (P-ERK), AKT and ERK2.