Abstract: Disclosed are methods and kits for measuring in situ the activity and amount of an enzyme in a sample using a single measurement system. The method includes the steps of: (a) contacting a sample to a capturing agent having the capacity to bind to the enzyme to be analyzed and immobilized on a solid matrix; (b) measuring the activity of the enzyme captured by the capturing agent; (c) contacting a detection antibody specific to the enzyme captured by the capturing agent; and (d) detecting an antigen-antibody complex formed in the step (c). There is no need for separate measurement system to measure the activity and amount of an enzyme, as well as the above methods and kits permit to measure the precise activity and amount of an enzyme simultaneously because the measurement of enzyme activity and amount is carried out in a single and same measurement system as to the same sample in almost simultaneous manner.

Abstract: There are provided a method of regulating a phosphorylated protein-mediated intracellular signal transduction comprising intracellularly expressing an antibody that specifically binds to the phosphorylated protein and an expression system for intracellular expression of the antibody. The method and system are effectively used in the investigation, prevention, or treatment of diseases caused by a phosphorylated protein-mediated intracellular signal transduction, including prostate cancer, lung cancer and breast cancer, through regulation of a molecular interaction involving a phosphorylated residue of the phosphorylated protein.