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.

[EX Q]: The antitussive activity of delta-opioid receptor stimulation in guinea pigs.
[EX A]: delta-opioid receptor

[EX Q]: Comparative study on transcriptional activity of 17 parabens mediated by estrogen receptor α and β and androgen receptor.
[EX A]: estrogen receptor α and β

[EX Q]: Anabolic effects of clenbuterol on skeletal muscle are mediated by beta 2-adrenoceptor activation.
[EX A]:
beta 2-adrenoceptor