More importantly, an increasing number of tyrosine kinase inhibitors (TKIs) are in development for the treatment of cancer [23,24,25], such as linifanib, targeting vascular endothelial growth factor (VEGF), which induces excessive angiogenesis in solid cancers; gefitinib and cetuximab, targeting epidermal growth factor receptor (EGFR) signaling in non-small cell lung cancer and metastatic colon cancer; and some that act on chronic diseases, such as imatinib, targeting platelet-derived growth factor (PDGF) signaling in pulmonary hypertension and respiratory dysfunction. The gene discussed is EGFR; the disease is pulmonary hypertension.