ERBB2 and acquired polycythemia vera: Unlike erlotinib and gefitinib, lapatinib inhibits human epidermal growth factor receptor 2 (HER2) that maybe responsible for the development of PH though further studies are needed [77].Another TKI that has been associated with PH is ruxolitinib, a Janus kinase (JAK) 1/JAK2inhibitor used in the treatment of myelofibrosis and polycythemia vera.