T47D/STAT3 Reporter (Luc) cells are derived from the human breast cancer T47D cell line by stably integration of a STAT3 firefly luciferase reporter construct. The T47D cell line represents luminal A subtype (ER+, PR±, HER2-) of breast cancer, making them a model for studying hormone receptor signaling and elucidating the progesterone-specific effects of a luminal A subtype of breast cancer. T47D/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.