For example, it acts as a receptor for certain coronaviruses10,11 and serves as a receptor for tumor-homing peptides, and it can be a target for inhibiting angiogenesis.12 Due to these functions, APN is sometimes classified as a so-called moonlighting enzyme—or more broadly, a moonlighting protein—terms that refer to enzymes or proteins with multiple, distinct functions.13 Here, ANPEP is linked to neoplasm.