TGFB1 and breast cancer: This effect is due to the complex interplay betweencysteine cathepsin activity, cystatin C, 14-3-3 proteins, and transforminggrowth factor beta (TGF-β) signaling pathways. Furthermore, the potential of cystatin-C as the BC monitoringmarkers at several time-points (at diagnosis, following preoperativechemotherapy, and at relapse) has been observed.