OMAHA, Neb. (AP) — The University of Nebraska has begun investigating questions raised about the integrity of a study conducted by University of Nebraska Medical Center researchers.

The American Journal of Respiratory and Critical Care Medicine published the study online in February. Questions have been raised since about the study and its data.

The study was done by five researchers from the Nebraska medical school and two from Temple University School of Medicine in Philadelphia. They studied the role of some proteins involved in a lung complication associated with the AIDS virus.

The journal issued an “expression of concern” on Aug. 1 and says print publication has been delayed.

Jim Turpen is associate vice chancellor for academic affairs at the Nebraska school, and he declined to comment.