COL9A1 and osteoarthritis: However, in our RNAseq analysis, other genes previously associated with OA such as SOX4, HIF-2α, or VEGF, are down-regulated following LSD1 inhibition, suggesting that this enzyme exerts a control of the cartilage integrity beyond the regulation of COL9A1. The in vivo investigation of its role toward osteoarthritis progression would thus be of great interest.