MMP13 and osteoarthritis, knee: Bravo et al. [32] have found that during IPFP-ASC chondrogenic differentiation, the expressions of PTFR and MMP13 are similar between the patients with knee osteoarthritis and the individuals with healthy knees, but the expressions of OPG, FGF2, TGF, and MMP3 are significantly lower in the patients with knee osteoarthritis than in the individuals with healthy knees.