CD9 and gastrointestinal stromal tumor: Given KIT’s role as a key GIST driver, we validated EV and cell lysate levels by western blot using standard markers (Alix, Calnexin, TSG101, Flotillin, Syntenin, CD9, and Cox) according to Minimal Information for Studies of Extracellular Vesicles (MISEV) guidelines [48].