Is it possible that a small protein goes through a nitrocellulose membrane? if the answer is yes, what´d it be the conditions that can be adjusted to prevent such passage.
did you used a 0.2 µm or 0.45 µm membrane? since the 0.45 µm pore membrane is used for most targets; because the 0.2 membrane is more efficient in binding smaller proteins, however, you can switch to it when probing for ones that are less than 15 kDa.