Problem:

EGFR (epidermal growth factor receptor) has been intensively studied in cancer and treatments have been developed to inhibit EGFR signaling. Sialylation of EGFR is known to block dimerization and down regulate signaling. I just read this paper:

Liu et al. 2011. Sialylation and fucosylation of epidermal growth factor receptor suppress its dimerization and activation in lung cancer cells. PNAS 108: 11332-11337. (basically just read conclusion if you don't have time).

What I don't understand is that the authors seem to say that increasing sialylation might be a good thing to prevent cancer progression since it inhibits EGFR dimerization. However, wouldn't this go against almost 50 or 60 years of research that suggest that increased levels of sialic acid are one of the well known hallmarks of cancer that aid in its progression and metastasis?

What could explain this apparent discrepancy? please explain.