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.

Example Input:  We have used the chloramphenicol acetyltransferase ( CAT ) reporter gene system to study the effect of T on the long terminal repeats ( LTRs ) of a large family of human endogenous retrovirus - like sequences , RTVL - H .
Example Output: chloramphenicol acetyltransferase

Example Input:  Transient transfection assays indicated that the ( - 4551 ) UCP1 - CAT construct , containing the 5 ' - regulatory region of the rat ucp - 1 gene , was activated by PPARalpha co - transfection in a dose - dependent manner and this activation was potentiated by Wy 14 , 643 and retinoid X receptor alpha .
Example Output: retinoid X receptor

Example Input:  Promoter activity of the proliferating - cell nuclear antigen gene is associated with inducible CRE - binding proteins in interleukin 2 - stimulated T lymphocytes .
Example Output:
interleukin 2