Interestingly, HER2 overexpression had limited effects on fibroblast proliferation (Fig. S4 F), whereas the in vitro invasion assay and in vivo SCID IPF mouse model showed an increased cell invasion index and abundant collagen deposition caused by the HER2 activated normal lung fibroblasts, demonstrated by a significant elevation in fibroblast invasion (Fig. 6, H and I) and a dramatic increase in lung fibrotic remodeling and hydroxyproline content (Fig. 6, J and K). The gene discussed is ERBB2; the disease is idiopathic pulmonary fibrosis.