RPMI-8226/STAT3 Reporter (Luc) cells are derived from the human myeloma RPMI-8226 cell line by stably integration of a STAT3 firefly luciferase reporter construct. The RPMI-8226 cell line is a valuable tool for understanding multiple myeloma and developing new treatments, including CAR-T (chimeric antigen receptor T-cell) therapy. RPMI-8226/STAT3 Reporter (Luc) cells stably express firefly luciferase under the control of the STAT3 response elements, can be used for monitoring the activity of STAT3 signaling pathway.