Lapatinib and IGF-I signaling

Lapatinib inhibits EGFR and HER2 signaling in trastuzumab resistant cells. Parental, pool 2, clone 3, and clone 4 cells were treated with 1 μmol/L lapatinib for 24 h. Immunoblotting (30 μg) was done (A) for phosphorylated and total HER2 and EGFR and (B) for the downstream signaling molecules, phosphorylated and total Akt, mitogen-activated protein kinase, and S6. Actin served as a loading control. Lapatinib inhibited EGFR and HER2 phosphorylation and blocked signaling pathway downstream of these receptors in parental and resistant cells.