What is the common shelf life of human antibodies stored at -20C? (if anyone knows specifically the shelf life for human TDP1 ab that would be great). Also, our lab has been using both yeast and human TDP1 abs for a long time in our western blotting and recently we had some trouble with our semi-dry transfer so we switched to the iBlot transfer cell. Our primary abs (human and yeast TDP1) are no longer showing up on the membrane. Any ideas?