Activation of multiple signaling molecules by vaccine-induced anti-HER2 antibodies and inhibition of activation by lapatinib. SK-BR-3 cells were left untreated (lanes 1 to 5) or were pretreated with 2 µM lapatinib for 3 hours (lanes 6 to 10) followed by 100 µg/ml vaccine-induced anti-HER2 antibodies (HER2-VIA) stimulation at 37ºC for the indicated time. After treatment, cells were washed and then lysed in 2 × SDS sample buffer followed by sonication. Equal amounts of protein from each sample were used to visualize the indicated molecules by immunoblotting. ERK, extracellular signal-regulated protein kinase.