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: Consider Input: T cell stage - specific PcG expression profiles suggest that PcG genes contribute to regulation of T cell differentiation .

Output: PcG genes

Input: Consider Input: Reactivity with the tegument protein encoded by UL21 was identified for an additional patient .

Output: tegument protein

Input: Consider Input: Both CD4 + and CD8 + T cells that produce IL - 2 in response to Ag recognition have been isolated .
Output: IL - 2