U266 SMAD/TGFbeta Reporter (Luc) cells are derived from the human myeloma U266 cell line by stably integration of a SMAD/TGFbeta firefly luciferase reporter construct. The U266 cells are an important tool in studying the pathogenesis, progression, and treatment of multiple myeloma, as well as for testing chemotherapies and immunotherapies, including monoclonal antibodies, immune checkpoint inhibitors, and CAR-T cell therapies. U266 SMAD/TGFbeta Reporter (Luc) cells stably express firefly luciferase under the control of the SMAD/TGFbeta response elements, can be used for monitoring the activity of TGF?/SMAD signaling pathway.