Professors Ahn Cu-rie and Yoon Hyeon-soo, two assistants of stem cell pioneer Hwang Woo-suk, on Thursday arrived in Cleveland, Ohio.

The two are believed to have headed for Pittsburgh via Chicago to meet three ethnic Korean researchers working under American scientist Gerald Schatten.

Schatten recently ended his 20-month partnership with Hwang over ethical reasons.

In Cleveland, Ahn and Yoon are expected to meet Hyeon In-soo, a bioethics expert at Case Western Reserve University who in August released a study on the ethical problems in Hwang's research.

A reporter is known to have accompanied Ahn and Yoon on their U.S. trip.