ERBB2 and cancer: The first TKI developed to target HER2 was lapatinib ditosylate, which restricts the phosphorylation of both HER1 and HER2 by reversibly and competitively occupying the ATP-binding sites of the intracellular kinase region and thus interfering with downstream signaling, which, in turn, leads to the induction of apoptosis and restriction of the growth and migration of cancer cells overexpressing HER2.