MMP2 and neoplasm: To demonstrate the advantage of the MMP-2-sheddable POLY-PROTAC for increased cellular uptake and deep tumour penetration (Fig. 3a), PGDA7 (with GG peptide spacer) and PDA7 (without GG peptide spacer) NPs were pretreated with MMP-2 for 1 h to cleave the PEG corona as reported previously39.