Use of EI24 gene

A method of diagnosing and treating EGFR-TKI drug resistance in an EGFR-TKI drug-administered patient, the method comprising:

• contacting a biological sample from an EGFR-TKI drug-administered patient with an antibody specifically binding to an EI24 protein and an antibody specifically binding to an insulin growth factor-1 (IGF-1) protein and detecting an expression level of the EI24 protein and the IGF-1 protein in the biological sample by detecting the antibody binding to the EI24 protein and to the IGF-1 protein;
• diagnosing the EGFR-TKI drug-administered patient as having EGFR-TKI drug resistance when the expression level of the EI24 protein is 5 times to 20 times lower than that of a control sample obtained from an EGFR-TKI drug resistance-free control group and the expression level of the IGF-1 protein is greater than that of a control sample obtained from an EGFR-TKI drug resistance-free control group;
• and
• administering an effective amount of EI24 and at least one selected from the group consisting of EGFR-TKI and an insulin growth factor-1 receptor (IGF-1R) inhibitor to the patient diagnosed as having EGFR-TKI drug resistance.