S100A9 and prostate carcinoma: In a concurrent experiment, they observed that circM1D1 downregulated MDSC exosome-mediated prostate cancer progression, and S100A9 from MDSC exosomal cargo was able to convert circM1D1 expression to sponge miR-506-3p, masking its antitumoral effects and effectively promoting prostate cancer cell progression (65).