Given an abstract from a research paper, your task is to identify and label relationships between chemical compounds and genes mentioned in the abstract.

The relationship type must be one of ['DOWNREGULATOR', 'SUBSTRATE', 'INDIRECT-REGULATOR', 'PART-OF', 'MODULATOR-ACTIVATOR', 'REGULATOR', 'INHIBITOR', 'COFACTOR', 'UPREGULATOR', 'ACTIVATOR', 'ANTAGONIST', 'NOT', 'INDIRECT-DOWNREGULATOR', 'SUBSTRATE_PRODUCT-OF', 'INDIRECT-UPREGULATOR', 'AGONIST', 'PRODUCT-OF', 'MODULATOR', 'DIRECT-REGULATOR', 'UNDEFINED', 'AGONIST-INHIBITOR', 'AGONIST-ACTIVATOR', 'MODULATOR-INHIBITOR'].

Please format your output as a JSON array. Each entry in the array should express a single relation, formatted as ["<Entity_A>", "<RELATION_A_B>", "<Entity_B>"]. If no relations can be found, please output an empty JSON array [].

Abstract:

Effects of long-term administration of UFT plus leucovorin on colorectal tumors induced with 1,2-dimethylhydrazine in rats. Thymidylate synthase and thymidine kinase are key enzymes involved in the de novo and salvage pathways for pyrimidine nucleotide synthesis, respectively. Thymidylate synthase is inhibited by 5-fluorodeoxyuridine monophosphate, forming an inactive ternary complex with intracellular folate. We investigated the effects of 1- (2-tetrahydrofuryl) -5-FU plus uracil (UFT) with or without leucovorin on 1,2-dimethylhydrazine-induced rat colorectal carcinomas. Thirty-week administration of UFT with or without leucovorin markedly suppressed both colorectal carcinogenesis and tumor growth, resulted in the increase of thymidylate synthase inhibition and the decrease of thymidine kinase activity in the tumor cells. These results indicate that the combination of UFT with leucovorin could be useful in the development of pre- and post-operative adjuvant chemotherapy programs.
[["pyrimidine nucleotide", "PRODUCT-OF", "thymidine kinase"], ["leucovorin", "INHIBITOR", "thymidylate synthase"], ["UFT", "INHIBITOR", "thymidylate synthase"], ["UFT", "INHIBITOR", "thymidine kinase"], ["pyrimidine nucleotide", "PRODUCT-OF", "Thymidylate synthase"], ["5-fluorodeoxyuridine monophosphate", "INHIBITOR", "Thymidylate synthase"], ["leucovorin", "INHIBITOR", "thymidine kinase"]]