Metastatic variants of murine cancer cell lines TSA1/E1, 4T1 and 4TO7 but not non-metastatic TSA1, 67NR and 168FARN also showed higher Padi4 (Extended Data Fig. 8c) and CitH3 upon ionophore treatment (Extended Data Fig. 8d,e). Here, PADI4 is linked to cancer.