GRN and rheumatoid arthritis: Furthermore, because links already exist between serum GP88 levels and disease progression or prognosis in malignancies (e.g., breast cancer [9,10,11], non-small-cell lung cancer [12] and prostate cancer [13,14]) and in the genesis and progression of other diseases (e.g., frontotemporal lobar degeneration [15,16], obesity [17,18], systemic lupus erythematosus [19,20] and rheumatoid arthritis [21,22]), changes in serum GP88 levels seem to reflect a pathophysiological state in a wide variety of conditions.