Figure 5

EGFR inhibition or silencing partially interferes with signal transduction in lapatinib-resistant breast cancer cells. (A) Western blot analysis of total cell lysates from MDA-MB-361, SKBR-3, MDA-MB-361-LR, and JIMT-1 human breast cancer cell lines grown in complete medium and treated with lapatinib (1 μM), cetuximab (0.35 μM), or the combination. (B) Western blot analysis on total cell lysates from MDA-MB-361, SKBR-3, MDA-MB-361-LR, and JIMT-1 human breast cancer cell lines transfected with an EGFR-specific siRNA (5 nM) and treated or not with lapatinib (1 μM). The relative optical density of phospho-protein levels normalized to the actin level is shown.