CD9 and cancer: In pancreatic ductal adenocarcinoma (PDAC), stromal expression of CD9 was associated with poor patient outcomes and cancer associated fibroblasts were found to release CD9-positive EVs which induced PDAC progression.55 In addition to CD9 EVs derived from tumor and stromal cells, there is evidence to support tumor cell activation of platelets and increased platelet EV release.56,57 Our current, and previous, work demonstrates that over half of the CD9 EVs in plasma are of platelet origin leaving the remaining being derived from other cell sources.