FAP and neoplasm: By loading fibroblast activation protein-α (FAP-α) antibody and CXCL12 siRNA onto the peptide nanoparticles (PNP), the nanosystem (PNP/siCXCL12/mAb) can selectively downregulate the expression of CXCL12 in CAFs via FAP-α recognition, causing inactivation of CAFs and blockade of CAFs-related tumor metastasis.