CD44 and neoplasm: Guiding by the external magnetic field, the magnetic iron oxide NPs-anchored T cells migrated to the solid tumor, where the CD44 was highly expressed by the tumor cells, the average fluorescence intensity of the magnet-placed side was 2.3 times higher than that of the non-magnet side, as shown in Fig. 5B. In the E.G7-OVA tumor model, the tumors in the NPs-anchored T cells group were smallest, demonstrating a distinct inhibitory effect (decreased by 105%) on solid tumors compared with standard adoptive T cell therapy.