Fig. (4) Expression of CCND1 protein in fresh or frozen human knee superficial and deep articular cartilage chondrocytes stimulated by culturing with Dulbecco's Modified Eagle's Medium (DMEM) with 10% fetal bovine serum (FBS). Protein concentrations were measured using a NanoDrop™ spectrophotometer and confirmed by western blot analysis. Data were normalized against the lowest value obtained for CCND1 protein expression levels, assigned the value of 1, and were measured as R.E.L.