To understand the role of multivalency on the intracellular uptake by human pancreatic cancer cell lines with variable EGFR expression, we treated AsPC-1, PANC-1 and MiaPaca-2 cells with GNP-C225 or nonspecific isotype control GNP-IgG at different antibody to GNP (Ab∶GNP) ratios. Here, EGFR is linked to familial pancreatic carcinoma.