Abstract: A sample preparation kit related to the present invention provides a significantly versatile analytical technique that is not affected by the diversity of antibodies, difference in species, matrix and the like. For preparing a sample to be used for detection of a monoclonal antibody through high-performance liquid chromatography-mass spectrometry (LC-MS), the kit includes a porous body for immobilizing a monoclonal antibody to be detected; nanoparticles with an immobilized protease; a reaction vessel for selectively digesting the monoclonal antibody by bringing the porous body and nanoparticles into contact; a buffer to be introduced into the reaction vessel along with the nanoparticles and porous body so that a protease reaction is carried out; and a filtration membrane to remove the porous body and nanoparticles after the proteolysis so as to extract the reaction product and the buffer.

Abstract: The present invention provides: a method for increasing a yield, from a target monoclonal antibody, of a peptide fragment that comprises an Fab region or a variable region of the antibody or a portion of the region, the method being characterized by including a process in which digestion of the target monoclonal body is performed by bringing the target monoclonal antibody, which is immobilized on inner surfaces of pores of a porous body, and a protease, which is immobilized on surfaces of nanoparticles having an average particle size larger than an average pore diameter of the porous body, into contact with each other in a liquid by stirring or tapping rotation stirring at a low speed of less than 100 rpm so as to maintain a uniform dispersion, the average pore diameter of the porous body being in a range of 10 nm-200 nm and the average particle size of the nanoparticles being in a range of 50 nm-500 nm; and a kit for use in the method.

Abstract: A method for detecting epithelial-mesenchymal transition of a cell includes measuring a level of serine in a metabolic substance mixture prepared from culture of the cell, and comparing the level of serine with a reference for serine such that epithelial-mesenchymal transition of the cell is detected based on at least the level of serine compared with the reference.