Our conclusion that the citrullination of matrisome proteins in cancer is mainly related to inflammation is based on the following facts: Firstly, analysis of cancer proteomics data sets revealed that many of the most frequently citrullinated matrisome proteins, such as fibrinogen and fibronectin, are also abundantly citrullinated in e.g., synovial fluid in rheumatoid disease (11). Here, FN1 is linked to cancer.