A longitudinal clinical study demonstrated the performance of the serum GP88 EIA by establishing a basal range for GP88 in serum from healthy volunteers of 28.7 ± 5.8 ng/ml and showing that serum GP88 levels in breast cancer patients was elevated to 40.7 ± 16.0 ng/ml in early stage and over 100 ng/ml in later stages of breast cancer [23]. Here, GRN is linked to breast cancer.