I am trying to do experiments that require WB using anti human CD44 antibody. The antibodies I have work really well for IF but as far as WB goes I am having a lot of difficulties. I repeat the same conditions and sometimes the antibody works great and some other times it only gives non specific staining. As I always carry a tubulin control I know the amount of protein in each well should be enough. Has anybody had this problem with an antibody before? What could be changing?