ADORA3 and malignant colon neoplasm: Moreover, radioligand binding experiments using the A3AR antagonist [3H]MRE 3008F20 and western blot analysis indicated that the A3AR is the most abundant of all four adenosine receptor subtypes in colorectal cancer tissues as well as in colon cancer cell lines (Caco-2, DLD-1 and HT-29).