A compound or its salts inhibiting the activity of the protein of the present invention, a compound inhibiting the expression of a gene for the protein, the antisense polynucleotide of the present invention, the antibody of the present invention, and the like can be used as prophylactic/therapeutic agents for neurodegenerative disease, diabetes and the like. A compound or its salts promoting the activity of the protein of the present invention, a compound promoting the expression of a gene for the protein, etc. can be used as prophylactic/therapeutic agents for cancer, rheumatic disease, etc.