The P-value is the probability U0126 ERK of deviation of the observed from expected due to chance alone or the contribution of some other factor. Our results indicate that the BC patients are not distinguishable from benign breast disease patients (P = 0.670) on the basis of differential expression of haptoglobin and the C8-containing fraction (SEB1). Similarly, there is no relationship between type of BC and expression of the SEB1 fraction (P = 0.102). However, expression of this fraction (SEB1) varies significantly (P = 0.005) depending on the status of chemotherapeutic treatment and HCV/HBV infection in BC patients. Our results correspond to earlier studies that have reported elevated serum levels of haptoglobin in various types of infections, inflammation and a wide range of carcinomas including BC,44 epithelial ovarian carcinoma,45 esophageal squamous cell carcinoma,46 urogenital tumor,47 leukemia,48 lung cancers and bladder cancers.

49,50 It is involved in the formation of the membrane attack complex on bacterial cell membranes. Alpha and beta subunits are responsible for the complement mediated bacterial killing but the gamma subunit appears to bind with retinol.51 In our study, the TTR (fraction SEB2) was the only identified protein that was found to be down-regulated in the majority of BC and benign breast diseases. It is a 55-kDa homotetrameric protein which plays an important role in the transport of thyroid hormones in blood36,52 and metabolism of retinol.

53 A scientific literature search has revealed that decreased levels of TTR have been reported in cases of severe liver diseases, malnutrition and acute inflammation54�C56 as well as in ovarian cancer,57�C59 lung cancer,60 cholangiocarcinoma,61 prostate cancer62 and advanced circular and endometrial carcinoma patients,58 but not in BC. Ours, therefore, is the first report to show that this protein is differentially expressed in breast diseases also. We also noticed a modified form of TTR (SEB3 fraction) being GSK-3 expressed in the sera of a few patients included in the study. In the published literature, TTR and its three post-translationally modified forms have been reported as serum markers in patients of mycosis fungoides, a type of cutaneous T-cell lymphoma.63 Post-translationally modified forms of TTR were also found in the serum of late-stage ovarian cancer, prostate, breast and colon cancer patients.36 We suggest that this protein may be a component of a cellular pathway that is common to the pathogenesis of different types of carcinoma. Earlier studies have reported �� and �� subunits of hemoglobin as potential serum biomarkers for the diagnosis and prognosis of ovarian cancer.