For the EGFR heterogeneity in lung cancer, recent reports have indicated that tumors are composed of mixed populations of mutant EGFR and wild-type EGFR cells, suggesting that the intratumor heterogeneity does indeed exist (Jiang et al., 2008; Taniguchi et al., 2008; Wei et al., 2014; Cai et al., 2015). Here, EGFR is linked to lung cancer.