The probe was constructed by connecting the following 3 main parts (Figure 1): the homing peptide CREKA, which is capable of targeting the tumor stroma, the cell-penetrating peptide Tat, and a linker (PLGLAG) that can be cleaved by matrix metalloproteinase-2 and -9 (MMP-2/9). This evidence concerns the gene MMP2 and neoplasm.