PTPN22 and neoplasm: Tumor‐homing peptides (such as iNGR, iRGD, and Lyp‐1) and tumor‐penetrating peptides (such as cell‐penetrating peptide (CPP)) have been reported to have tumor homing and tumor penetrating capabilities.[25, 92] In recent years, the research of tumor‐homing and tumor‐penetrating peptides has mainly focused on tumor targeting and tumor penetration by using their tumor‐homing ability and on the modification of peptides to obtain a better tumor microenvironment response.