Issues

A multiplex tissue immunoblotting analysis of phospho-mTOR in extrahepatic cholangiocarcinoma. Multiplex tissue immunoblotting is a method of transferring proteins from a formalin-fixed, paraffin-embedded tissue section to a stack of replicate membranes, which can then be probed with antibodies by conventional immunoblotting methods. Using this approach, total protein and target antigen signals can be simultaneously determined on each membrane as a means of normalization. As the membranes are replicates, ratio-based measurements of different target antigens can be made. The cover image is a scan of a single membrane, probed with a fluorescent secondary antibody, showing the relative signal as visualized by pseudo-color, where signal intensity is white-red-yellow-green-blue-black from maximum to minimum signal. The ratios of different proteins in the AKT pathway predict survival in extrahepatic cholangiocarcinoma. For further details, please see Chung and coworkers on page 660 in this issue.