FN1 and breast cancer: Additionally, Xiong et al. demonstrated that DOX-loaded hydroxyapatite (HP) nanoparticles modified with a high-affinity peptide for FB-FN called CREKA (Cys-Arg-Glu-Lys-Ala) peptide could bind and damage the primary tumor and PMN in 4T1 lung metastasis model, thus inhibiting the BC metastasis 134, 135.