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]: Mifepristone alters expression of endometrial steroid receptors and their cofactors in new users of medroxyprogesterone acetate.
[EX A]: steroid

[EX Q]: Inhibition of Th1/Th17 responses via suppression of STAT1 and STAT3 activation contributes to the amelioration of murine experimental colitis by a natural flavonoid glucoside icariin.
[EX A]: flavonoid

[EX Q]: The effect of estramustine derivatives on microtubule assembly in vitro depends on the charge of the substituent.
[EX A]:
estramustine