ROR1 and neoplasm: Our cell experiments also showed the ROR1 mRNA and protein expression was significantly up-regulated in EGFR-TKIs-resistant cells, but its expression level in exosomes was significantly lower than that in cells, which indicated that ROR1 mRNA and protein are not secreted in the form of exosomes by EGFR-TKIs-resistant cells to the tumor microenvironment.