CD39contributestoimmuneregulationthroughthehydrolysisofATPtoAMPintheratelimitingstepofextracellularadenosineproduction.CD39isexpressedonthesurfaceofmultiplecellsoftheimmunesystemincludingT-cells,Naturalkillercells,B-cells,dendriticcellsandmacrophages.Inaddition,highlevelsofCD39expressionhavebeenassociatedwiththetumormicroenvironment(TME).ResearchaimedatreducingimmunosuppressionbyCD39activityhasresultedinthestudyofasmallmoleculeinhibitor,POM1,andmultipleanti-CD39antibodiesselectedforblockingenzymaticactivity ordecreasingCD39expression.