The expression levels of Trop-2, CEACAM6, HLA-DR, and EGFR on the cell surface of seven human cancer cell lines (cervix, ME-180; esophagus, TE-11; lung, A549, SK-MES-1; liver, HepG2, Huh-7; and melanoma-skin, A375) were determined by flow cytometry with hRS7, hMN-15, hL243, and h225 as the probing antibodies. The gene discussed is CEACAM6; the disease is cancer.