CD44 and neoplasm: By thoroughly understanding the mechanisms behind the internalization of HA-modified NGs into the MDR MCF-7/ADR tumor cells, researchers found that MCF-7/ADR and MCF-7 tumor cells overexpressed CD44 receptors, so that drug-loaded HA-modified NGs were efficiently internalized by tumor cells because of strong affinity of HA towards CD44 receptors which facilitated selective internalization of their cargo into CD44 + tumor cells.