Given a context passage, generate a question from the passage such that its answer is shortest continous span from the passage.

Let me give you an example: In 1582 the united provinces invited francis, duke of anjou to lead them; but after a failed attempt to take antwerp in 1583, the duke left the netherlands again. after the assassination of william of orange (10 july 1584), both henry iii of france and elizabeth i of england declined the offer of sovereignty. however, the latter agreed to turn the united provinces into a protectorate of england (treaty of nonsuch, 1585), and sent the earl of leicester as governor-general. this was unsuccessful and in 1588 the provinces became a confederacy. the union of utrecht is regarded as the foundation of the republic of the seven united provinces, which was not recognized by the spanish empire until the peace of westphalia in 1648.
The answer to this example can be: In what year did francis, duke of anjou leave the netherlands?
Here is why: The generated question is perfect. Because the question is based on second sentence of the input passage and its answer is 1583.

OK. solve this:
Patients with lung adenocarcinoma who carry epidermal growth factor receptor (EGFR) gene mutations respond remarkably well to EGFR tyrosine kinase inhibitor (EGFR-TKI), gefitinib, or erlotinib. However, the effect of EGFR-TKI treatment on the prolongation of overall survival (OS) of these patients remains uncertain, although several recent studies have shown prolongation of progression free survival compared with cytotoxic chemotherapy. A total of 304 patients with lung adenocarcinoma who had postoperative recurrent disease were studied. To eliminate potential biases as possible, the matching of four potential predictive factors of responsiveness to EGFR-TKI led to the identification of 81 pairs of patients (those who were treated with gefitinib and those who were not). A deletion mutation in exon 19 and a point mutation (L858R) in exon 21 of the EGFR gene were also analyzed. We compared the OS between the two groups. OS in the gefitinib group was significantly longer than in the control group (median, 63 vs. 41 months; p=0.015). EGFR mutations were detected in 65 out of 129 patients (50%) in the whole sample. EGFR mutational status was not an independent prognostic factor of gefitinib benefit; rather, it was a predictive factor. This study strongly suggested that gefitinib treatment improved OS of lung adenocarcinoma patients who had postoperative recurrence, especially those carrying EGFR mutations.
Answer:
Mutations in which gene determine response to both erlotinib and gefitinib?