NEU4 and colonic neoplasm: Here we found that serum starvation in colon cancer cells reduced the amount of sialyl Lewis X but not sialyl Lewis A. NEU4 may regulate both sialyl Lewis A and sialyl Lewis X, but starvation-related NEU4-mediated up-regulation did not influence sialyl Lewis A. This means that serum starvation may influence other key glycan-synthesizing enzymes that are specific for sialyl Lewis A, such as ST3GAL3, B3GALT5 or FUT344–46, to overcome the NEU4 effect on sialyl Lewis A expression.