Retinoic acid stimulates chondrocyte differentiation and enhances bone morphogenetic protein effects through induction of Smad1 and Smad5.
Li X, Schwarz EM, Zuscik MJ, Rosier RN, Ionescu AM, Puzas JE, Drissi H, Sheu TJ, O'Keefe RJ. Retinoic acid stimulates chondrocyte differentiation and enhances bone morphogenetic protein effects through induction of Smad1 and Smad5. Endocrinology. 2003 Jun; 144(6):2514-23.