The cellular uptake behaviors and intracellular localization were observed from the Dox signal using full spectrum fluorescence microscopic imaging system (Figure ). After incubation for 10 h, 4T1 tumor cells treated with P-T-Dox@CM nanogels exhibited much higher Dox fluorescence inside cells compared with that of the P-TN-Dox nanogels, validating the cancer cell membrane cloaking significantly enhanced the cellular internalization of nanogels thanks to homotypic targeting ability derived from the active cancer cell membrane proteins such as TF-antigen and E-cadherin. As confirmed by the fluorescent signals from LysoTracker, a marker of lysosome and late endosome staining, the P-TN-Dox and P-TN-Dox@CM nanogels showed good colocalization with lysosomes (or late endosomes), displaying the cellular internalization of nanogels by endocytosis and entrapment with endo/lysosomal trafficking. These results indicate that the source tumor cell membrane modification on the nanogels could play a vital role in enhancing the loaded Dox delivery into the tumor cells.