.For my research project, I need to isolate extracellular vesicles from MDA-MB-231 cell cultures using size-exclusion chromatography. The samples were collected in 24 fractions and to elucidate the EV-associated membrane proteins (CD9, CD63, and CD81) in the SEC fractions, Dot blot was performed.

However, after the imaging, I see signals in fractions 15 to 24, which is really strange because EVs are supposed to be collected in fractions 8 to 13 and after fraction 15 you wouldn't normally see signals.

I'm not sure what would be the cause of this.