Given that high levels of Cathepsin in tumor tissues can specifically cleave a tetra-peptide linker GFLG (Özel et al., 2015), Cheng (Cheng et al., 2020) constructed a tumor cell and mitochondrial dual-targeting nano-platform based on PpIX-GGGK (TPP)GG-GFLG-R7-RGD for the co-delivery of DOX and protoporphyrin IX (PpIX). This evidence concerns the gene CTSS and neoplasm.