GFB is a first-generation tyrosine kinase inhibitor (TKI), reversibly inhibiting EGFR autophosphorylation and downstream mitogen-activated protein kinase/phosphatidylinositol 3-kinase (MAPK/PI3K) signaling in EGFR-overexpressing cancers (breast, lung, colon, brain). The gene discussed is EGFR; the disease is cancer.