In this task, you are given a sentence. You are expected to recognize the name of any form of chemical substances. Although there might be several correct answers, you need to write one of them.

[Q]: Nicotine-induced contraction in the rat coronary artery: possible involvement of the endothelium, reactive oxygen species and COX-1 metabolites.
[A]: oxygen


[Q]: Distinct role of PYK2 in mediating thromboxane generation downstream of both G12/13 and integrin αiibβ in platelets.
[A]: thromboxane


[Q]: Drug-drug interactions between HMG-CoA reductase inhibitors (statins) and antiviral protease inhibitors.
[A]:
HMG-CoA