MMP2 and lung cancer: The resulting NH2/MAL Mn3O4 NPs were then modified first with a MMP2 cleavable peptide (Fig. 1b) and then with luteinizing hormone-release hormone (LHRH) receptor targeting peptide (Fig. 1c; please note a thioether linkage of maleimide moiety on DSPE-PEG molecule with a cysteine residue on the LHRH peptide) to enable active targeting to ovarian and lung cancers (12).