Verification of the OA-dependent alteration of HPT by Western blot analyses of independent samples. (A) Representative image obtained from the DIGE gels, together with the quantitative data acquired thereof for Haptoglobin beta chain (HPT, which was increased in OA samples). (B) Proteins in crude serum samples from OA patients (n = 15) and controls (N, n = 15) were resolved by SDS-PAGE and probed with antibodies against HPT. Band intensities were normalized against the intensity of Ponceau staining (upper figure). (C) Semi-quantitative densitometric analysis of the blot signals confirmed the increase of HPT beta chain in OA sera.