PTGS2 and neoplasm: Pre-administration of 2 mg of celecoxib to each of the mice used in the experiment resulted in a 16% decrease in tumor uptake of the tracer at 1 h p.i. Selective COX-2-mediated uptake of the tracer in HCA-7 tumors was showed in a biodistribution study carried out on celecoxib-treated and control HCA-7 tumor-bearing NIH-III mice, which showed a 50% blocking effect by celecoxib.