As the important role of ATX in chronic inflammation and cancer is emerging, a large number of ATX inhibitors have been developed over the last years [2, 20], while several of them have exhibited therapeutic potential: in air-pouch inflammation [39], collagen-induced arthritis [43], bleomycin-induced pulmonary inflammation and fibrosis [14], allergen-induced asthma [44], as well as in the metastasis of melanoma and breast cancer cells [41, 45–48]. Here, ENPP2 is linked to Arthritis.