The decreased secretion by nicotine (10−8 to 10−7 M) in a high concentration of MMP1/MMP13 and two proposed markers of osteoarthritis, fibronectin (FINC) and chitinase 3-like protein 1 (CHI3L1), in primary chondrocytes from patients also reminded us of the cautious and judicious use of nicotine in osteoarthritis treatment (71). The gene discussed is MMP13; the disease is osteoarthritis.