The present study shows that migration ability was higher in MDA-MB-231 cells carrying a S379 phosphorylation-defective hnRNPK gene (MDA-MB-S379A cells) than in cells carrying either the wild-type hnRNPK (MDA-MB-WT cells) or cells carrying a S379 phosphorylation-mimic hnRNPK gene (MDA-MB-S379D cells), which implies that hnRNPK S379 phosphorylation negatively regulates cancer cell migration. The gene discussed is HNRNPK; the disease is cancer.