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.

 These results suggest that TCF - 1 does not target human killer immunoglobulin receptor genes , TCF - 1 is uniquely expressed in circulating CD56 ( + bright ) NK cells , and specific TCF - 1 isoforms may play an important role in regulating NK differentiation from a common NK / T - cell progenitor .
TCF - 1