Western blot analysis of endogenous CK19 expression in colonic tumor specimens. Six colonic tumor specimens from one patient (01) at Dukes' stage B, three (02-04) at stage C, and two (05 and 06) at sage D were all under the age of 60 years. Two of patients (patients 02 and 03) presented with a monotypic band at 40 KDa (CK19) and others produced heterotypic bands at 40 KDa and ~37 KDa. The molecular weight of Actin was 43 KDa. Antibodies, mouse anti-human CK19 antibody or rabbit anti-human Actin antibody. P, HT-29 cells served as the positive control.