A protein found inside the nucleus of a cell. It is involved in making DNA, RNA, and proteins. It also helps control how certain genes are expressed (turned on) in a cell. Nuclear matrix protein 22 may be found in higher than normal amounts in the urine of patients with some types of cancer, including bladder cancer. Measuring the amount of nuclear matrix protein 22 in the urine may help diagnose cancer or find out how well treatment is working. It is a type of tumor marker. Also called NMP22.