Inspired by the concept of protein-based delivery named “Drug-delivering-drug”, as we previously investigated [94], dual-functional transferrin was selected as the protein carrier for PTX and the targeting ligand for transferrin receptors overexpressed on cancer cells, to achieve a decent drug loading of 16.7% and a fine self-assembly with LTSLs by electrostatic interaction in this study (Figure 2A). Here, TF is linked to cancer.