Most adenocarcinomas expressed MUC21 (if tumors with very focal expression were included, a positive frequency, for example MUC21 expression detected by the polyclonal antibody, was 77.6% (187/241) of whole LADCs, and 87.1% (101/116) of EGFR-mutated LADCs). Here, EGFR is linked to adenocarcinoma.