Data from the most recent study confirmed that depletion of FAP expressing fibroblasts in an arthritis model was not systemically toxic.[4] In serum transfer arthritis model in transgenic FAP luciferase diphtheria toxin receptor reporter mice, FAP expressing cells were depleted by injection of diphtheria toxin after arthritis is established and arthritis was diminished, but no weight loss nor other signs of cachexia were observed.[4] Additionally, no signs of toxicity were observed in our models (data not shown). The gene discussed is FAP; the disease is Arthritis.