It has been found that lapatinib can reduce the phosphorylation of EGFR and HER2, block Akt, MAPK, and mTOR signaling pathways, resist the inhibitory effect of insulin-like growth factor I (IGF-I) signal, promote apoptosis of BC cells, and reverse the therapy resistance of HER2-positive BC to trastuzumab [224]. The gene discussed is ERBB2; the disease is breast cancer.