SOX9 and neoplasm: Our in vitro data with chondroprogenitor cells in micromass cultures suggest that LDN-193189 likely inhibited tumor formation by reducing chondrogenic mechanisms including Sox9 expression and pSMAD1/5/8 signaling [32, 55] while enhancing anti-chondrogenic pathways including pERK1/2 signaling and Fgf gene expression [54, 61, 62].