TYMP and neoplasm: Considering that inhibitors of TP activity could suppress angiogenesis, and consequently tumour growth and metastasis in TP-expressing tumours, we developed a novel selective inhibitor of TP (TPI; 5-chloro-6-(2-iminopyrrolidin-1-yl) methyl-2,4 (1 H,3 H)-pyrimidinedione hydrochloride; Ki = 2 × 10−8 M)7, which has several advantages over previously described inhibitors of TP.