ENTPD1 and neoplasm: Interestingly, we further noted that the numbers of CD39+Tregs and Th17 cells are inversely correlated in MPE, and that the ratios of CD39+Tregs/Th17 cells were significantly lower in MPE than in blood, suggesting that there could be a dynamic interaction between Th17 cells and CD39+Tregs in the tumor microenvironment.