The company initially apologized by criticizing the University of Illinois' enrollment choices.
The Illinois' attorney general is investigating a transportation company that promised patrons "you won’t feel like you’re in China" on its buses.
Suburban Express, which provides bus services to University of Illinois students, emailed out the controversial line as part of an ad for its services last weekend.
In response, Attorney General Lisa Madigan announced a subpoena for Suburban Express on Monday and will be looking at whether the ad breached Illinois' Human Rights Act. The act prohibits services from being denied based on a number of factors, including race and national origin.
"I am concerned that this advertisement may reflect that Suburban Express is discriminating against potential customers," Madigan said in a statement. "Under the law, access to transportation must not be impacted or based on a person's race or national origin. My office is investigating to determine whether Suburban Express' policies and practices violate the law."
China's state-run news agency Xinhua reported the "racist" message along with a claim from a Chinese PhD student that they will no longer use the service.
An initial apology from Suburban Express criticized the University of Illinois' enrollment of foreign students.
A second apology, on Facebook, admitted the ad was "grotesquely xenophobic" and that the company admits all responsibility for its "inappropriate and harmful" actions.
Representatives for the University of Illinois released a statement that said the "offensive, bigoted, insulting" messages of Surburban Express, which is not affiliated with the university, "insulted members of our Chinese, Asian and Asian American communities."
The statement also alleged that the bus company has a "long history of taking advantage of students, staff and faculty."