Figure 5

Intracellular signaling changes induced by lapatinib in A549 cells, analyzed by western blot. A. Immunoblots showing decreased levels of p-EGFR and p-HER-2 after stimulation with 100 ng/ml EGF and treatment with lapatinib. Downstream targets p-AKT, p-ERK1/2, c-Myc and PCNA were also reduced upon exposure to the drug. B. After lapatinib treatment, the proapoptotic protein Bak-1 was increased, the levels of the antiapoptotic proteins IAP-2 and Bcl-xL were reduced, and PARP was cleaved, thus demonstrating that the apoptotic pathway is switched on by this drug in A549 lung cancer cells.