E0771/STAT3 Reporter (Luc) cells are derived from the mouse mammary adenocarcinoma cell line E0771 by stably integration of a STAT3 firefly luciferase reporter construct. E0771 cells are frequently used as a preclinical model for studying breast cancer, particularly in the context of tumor biology, metastasis, and therapeutic interventions. E0771/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.