T47D/RFP cells are derived from the human breast cancer T47D cell line by stably integration of a constitutive RFP stably expression 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/RFP cells stably express RFP, can be used for in vitro assays and in vivo imaging.