1191
Recent evidence suggests that a substantial portion of the passive stiffness of an in vitro preparation of tracheal smooth muscle is calcium sensitive and is regulated by Rho - kinase , although the underlying mechanism and the details of regulation for the development of this intracellular passive stiffness are still largely unknown .
 Chemical: calcium
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: calcium