Thus, we transiently reduced SOX9 expression in a chondrosarcoma cell line (HTB94, derived from a G2 chondrosarcoma) via siRNA, leading to a decrease in SOX9 gene expression (Supplementary Figure S3A) and accordingly, to decreased protein expression by 80–90% compared to control cells (non-targeting siRNA = nt) (Figure 2A). Here, SOX9 is linked to chondrosarcoma.