On the one hand, YY1 is highly expressed in prostate cancer, gastric cancer, ovarian cancer, breast cancer, multiple myeloma, liver cancer, and lung cancer etc. It especially shows increased expression in metastases compared with primary tumors, suggesting that high expression of YY1 may be a molecular marker for early diagnosis and prognosis evaluation of these tumors. This evidence concerns the gene YY1 and AL amyloidosis.