ATDC5/RFP cells are derived from the mouse teratocarcinoma ATDC5 cell line by stably integration of a constitutive RFP stably expression construct. ATDC5 cell line is characterized as a chondrogenic cell line which goes through a sequential process analogy to chondrocyte differentiation. It is a well established in vitro model of endochondral ossification. ATDC5/RFP cells stably express RFP, can be used for in vitro assays and in vivo imaging.