Instructions: In this task, you are given a sentence. You are expected to recognize the name of gene or protein. Although there might be several correct answers, you need to write one of them.
Input: Keywords included reperfusion injury , transplantation , liver resection , nitric oxide , endothelin , cytokines , Kupffer cells , ischemic / ischaemic preconditioning , and nuclear factor - kappa B .
Output:
nuclear factor