TT/iRFP cells are derived from the human medullary thyroid carcinoma (MTC) TT cell line by stably integration of a constitutive miRFP670 stably expression construct. TT cells have been widely used for medullary thyroid carcinoma (MTC) research, particularly in studies related to calcitonin production, tumorigenesis, and the development of targeted therapies. Its ability to secrete calcitonin and form tumors in vivo makes it a valuable model for both in vitro and in vivo studies of MTC biology and treatment. TT/iRFP cells stably express miRFP670, can be used for in vitro assays and in vivo imaging.