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.

[EX Q]: Mercury induces the expression of cyclooxygenase-2 and inducible nitric oxide synthase.
[EX A]: nitric oxide

[EX Q]: Oxytocin receptor binding and uterotonic activity of carbetocin and its metabolites following enzymatic degradation.
[EX A]: carbetocin

[EX Q]: RDH12, a retinol dehydrogenase causing Leber's congenital amaurosis, is also involved in steroid metabolism.
[EX A]:
retinol