The presence of exosomal CD9 and the absence of exosomal ADAM17 reduced the adhesion of primary mesothelial cells to exosomes produced by CRC Colo-320 cells. (A) Flow cytometry detection of CD9, CD81, integrin β1, integrin α5, ADAM17, and fibronectin on the surface of primary mesothelial cells from three different donors. (B) Adhesion of primary mesothelial cells (from the three patients in (A)) to immobilized exosomes produced by Colo-320 cells in presence of blocking mAbs specific for β1 integrin, α5 integrin, fibronectin and the Dis domain of ADAM17. (C) Adhesion of primary mesothelial cells (from the three patients in (A)) to immobilized exosomes produced by Colo-320, Colo-320/CD9 and Colo-320/ADAM17-KO cells. The percentage of cells that remained adhered is indicated as mean ± SEM of three experiments (one for each patient), performed in duplicates. Statistical analysis performed was one-way ANOVA. *** p < 0.001, **** p < 0.0001, ns: not statistically significant.