The design strategy of this nanocarrier is harnessed the proteinase MMP‐2, which is highly expressed in the tumor extracellular matrix, to trigger the size‐shrinkage of HA‐pep‐PAMAM from 200 to 10 nm because of cleavage of peptide linker (PLGLAG), thereby facilitating penetration into deep tumor tissues. The gene discussed is MMP2; the disease is neoplasm.