ENPP2 and cholestasis: In recent years, the neuronal activator lysophosphatidic acid (LPA) and its forming unit autotaxin (ATX) have been shown to be key factors in the cholestasis-associated pruritogenic signal cascade, and serum ATX levels have been reported to correlate with the level of pruritus.5 Thus, ATX levels can potentially be used to monitor the response to conventional medical treatment of cholestatic itching.