Researchers at Yashraj Biotechnology Ltd. developed a CA15-3 like recombinant antigen (MUC1RS), containing ten MUC1 tandem repeats, and expressed it in CHO-K1 mammalian cells with a Gaussia luciferase signal sequence for secretion and proper post-translational modifications. A high-expressing clone was selected, adapted to low-serum culture, scaled up and purified by anion exchange chromatography. The protein was characterized by western blot and confirmed to carry epitopes recognized by the DF3 and 115D8 antibodies on ELISA and Siemens CLIA platforms, supporting its potential use in breast cancer diagnostic assays.