Cell-permeable. A second-generation inhibitor of the ErbB family of receptor kinases. Neratinib acts as an irreversible inhibitor of the epidermal growth factor receptor (EGFR) and human epidermal growth factor receptor 2 (HER-2) tyrosine kinases by targeting a cysteine residue in the ATP-binding site of the receptor. It inhibits the proliferation of HER-2 overexpressing human breast cancer cell lines and EGFR-dependent cells in vitro.