EGFR and cancer: Gefitinib and paclitaxel are reversible epidermal growth factor (EGF) receptor-specific tyrosine kinase inhibitors (EGFR-TKIs) and are considered as first-generation EGFR-TKIs; second-generation EGFR-TKIs are currently being developed to overcome drug resistance3, which is caused in part by cancer stem cells (CSCs).