Furthermore, we demonstrated that X-NP-DOX crosslinked HA, which could bind to CD44 on the surface of CD44hi HCT-116 cells or MCF-7 cells, treatment resulted in increased DOX endocytosis compared with free DOX; whereas, lower pericellular DOX distribution was seen in CD44lo T47D cells with X-NP-DOX than that incubated with free DOX, suggesting that X-NP-DOX was taken up by tumor cells via CD44 receptor-mediated mechanism. The gene discussed is CD44; the disease is neoplasm.