The irreversible pan-PAD inhibitor Cl-amidine is perhaps the most widely used compound to study the role of PAD enzymes in normal and pathological states, and has been shown to ameliorate disease severity in a number of animal studies, including mouse models for breast cancer, prostate cancer and glioblastoma [37,181,184–186]. The gene discussed is PADI4; the disease is prostate carcinoma.