Mellinghoff et al. treated 49 recurrent glioblastoma patients with erlotinib (at doses from 150 to 500 mg) and gefitinib (from 150 to 1000 mg), and found that PTEN loss was associated with resistance to EGFR tyrosine kinase inhibitors [73]. The gene discussed is EGFR; the disease is glioblastoma.