CTLA4 and prostate cancer: We then analyzed the effect of CD on SOX9 expression levels in tumor cells and showed that CD dose-dependently decreased the protein of SOX9 and its mRNA expression levels in 22RV1 (Figures 5A, B), PC3 (Figures 5C, D), and H1975 (Figures 5E, F) cells, indicating that CD inhibited SOX9 expression in tumor cells, especially in prostate cancer cells.