We can detect the position of tumor cells/tissues and the situation of malignancy based on the abnormal expression of these substances [23], for example, cyclooxygenase-2 (COX-2), nitroreductase (NTR), pH, GSH, other biothiols, H2S, H2O2, HOCl and nicotinamide adenine dinucleotide (NADH). This evidence concerns the gene PTGS2 and neoplasm.