MMP2 and central nervous system cancer: The surface of the gelatine NPs was conjugated with gold NPs carrying doxorubicin and a glioma‐targeting peptide RRGD (G‐AuNPs‐DC‐RRGD), where RRGD presents the conjugation of R8 (RRRRRRRR) to cyclic RGD peptide with a terminal cysteine (Cys‐c(RGDfK), cysteine was conjugated to the branch of lysine).[284] The NPs originally had a size of 188 nm, but in the presence of MMP‐2, they shrank to 55 nm.