ENTPD1 and clear cell renal carcinoma: CD39 is expressed in infiltrating immune cells as well as on the cancer cells in a range of human cancers, including lung cancer, squamous cell carcinoma of the head and neck, clear cell carcinoma of the kidney, rectal adenocarcinoma, thyroid cancer, breast cancer, and multiforme glioblastoma solid tumors, studies have shown that high expression of CD39 is strongly associated with adverse outcomes [67].