ALPL and hyperinsulinemic hypoglycemia, familial, 4: hMSCs have been reported to spontaneously release ATP,19 and ATP levels may dramatically increase when the microenvironment is changed.25,53 Moreover, extracellular ATP can, in turn, affect the function of MSCs, including inhibiting proliferation,19 stimulating migration54 and regulating differentiation.55,56 Here, we found that Alpl deficiency leads to an elevated extracellular ATP concentration primarily due to increased ATP release and decreased ATP hydrolysis.