The famous Chinese artist and political dissident Ai Weiwei hasn’t been heard from since his arrest Sunday by Chinese authorities. The disappearance of Mr. Ai, who uses his art to express political dissent, is just one of a slew of recent arrests by the Chinese government in what seems to be a bid to prevent protests inspired by the Middle East uprisings to China. Ai has long been at odds with the Chinese government, and this isn’t the first confrontation.

What has made Ai a marked man in China?