To assess the role of the EGFR-L858R mutation in cancer cell invasion ability and involvement in the formation of MPE, we used two H1299-derived NSCLC cell lines—H1299-EGFR-WT, overexpressing wild-type EGFR, and H1299-EGFR-L858R, overexpressing EGFR-L858R—as a model system. Here, EGFR is linked to cancer.