Abstract: The present invention provides a technology for performing a test for prostate cancer. This method is for testing the possibility of having prostate cancer, the method comprising (1) measuring the amount or concentration of a biomarker in a body fluid sample collected from a subject, the biomarker being at least one member selected from the group consisting of dimethyl glutarate, 2,6-xylidine, 2-hydroxy-2-methylpropiophenone, 2,6-di(propan-2-yl) phenol, dimethyl succinate, acetophenone, 2-phenyl-2-propanol, and 3,5,5-trimetyl-2-cyclohexenone.

Abstract: An object is to provide a technique of increasing the response activity of an olfactory receptor to a chemical substance, and the object is achieved by introducing a mutation into a specific site in an insect olfactory receptor protein so as to satisfy a specific condition.

Abstract: An object is to provide a technique for detecting a nitro compound. The object is achieved by a nitro compound detection element formed from a specific type of an insect olfactory receptor or from an insect olfactory receptor having a specific mutation introduced.