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.

Example Input: Estradiol replacement enhances cocaine-stimulated locomotion in female C57BL/6 mice through estrogen receptor alpha.
Example Output: estrogen

Example Input: Increased Cat3-mediated cationic amino acid transport functionally compensates in Cat1 knockout cell lines.
Example Output: amino acid

Example Input: Plasmacytoid dendritic cells produce cytokines and mature in response to the TLR7 agonists, imiquimod and resiquimod.
Example Output:
imiquimod