TTR and neoplasm: Some studies have demonstrated that CD39 was implicated in promoting tumor growth and metastases through the suppression of antitumor immune responses and enhancement of angiogenesis.[29,30] Extracellular ATP directly limits tumor cell growth and these antitumor effects can be mitigated by provision of CD39 or by the intrinsic EC expression of CD39.[24] Our study found that CD39 was mostly expressed on ECs, which probably played an important role in the progression of HCC; this is in agreement with our data on the levels of tumoral CD39 expression which were shown to be related to TTR and OS.