COL2A1 and Alzheimer disease: Importantly, this gene-expression analysis (as assessed by using both conventional and novel NP markers, as well as ACAN-to-COL2A1 ratio) has shown that GDF6 promotes discogenic differentiation of both BM-MSCs and AD-MSCs, with gene-expression changes being greatest in AD-MSCs, suggesting that these cells may be more able to differentiate to an NP-like phenotype.