instruction:
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.
question:
 This suggests the association of E2 - receptor expression with control of growth rather than cell maturation .
answer:
E2 - receptor


question:
 To investigate the role of costimulation of OX40 in human immunodeficiency virus type 1 ( HIV - 1 ) infection by its natural ligand , gp34 , the OX40 - transfected ACH - 2 cell line , ACH - 2 / OX40 , chronically infected with HIV - 1 , was cocultured with paraformaldehyde ( PFA ) - fixed gp34 - transfected mouse cell line , SV - T2 / gp34 .
answer:
HIV - 1


question:
 Thus , despite the less stringent requirement for PU . 1 in NK cell development compared to B and T cells , PU . 1 regulates NK cell differentiation and homeostasis .
answer:

PU . 1