TASK DEFINITION: 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.
PROBLEM: Development of hypoxia-inducible factor (HIF)-1α inhibitors: effect of ortho-carborane substituents on HIF transcriptional activity under hypoxia.

SOLUTION: ortho-carborane

PROBLEM: Compensatory changes in enzymes of arginine metabolism during renal hypertrophy in mice.

SOLUTION: arginine

PROBLEM: Rat hepatic stellate cells become retinoid unresponsive during activation.

SOLUTION:
retinoid