Lapatinib effectively inhibits the epidermal growth factor receptors, ErbB1 (EGFR) and ErbB2 (HER2) in breast cancer cells.24, 25 To determine whether these receptors have a role in siramesine and lapatinib-induced cells death, we knocked down HER2 alone, EGFR alone, and then EGFR and HER2 together through transiently using siRNA in MDA MB 231 cells. The gene discussed is ERBB2; the disease is breast cancer.