Dr. Alfred Gilman, a 1994 Nobel Prize-winning scientist and former dean of the University of Texas Southwestern Medical School, has died after a lengthy illness. He was 74.

Russell Rian, a spokesman for UT Southwestern in Dallas, said Thursday that the university learned of Gilman's death from his family on Wednesday.

Gilman shared the Nobel Prize in Physiology or Medicine with Dr. Martin Rodbell of the National Institute of Environmental Health Sciences for their discovery of G proteins.

Such proteins help in the process of receiving signals from outside the cell and activating responses.

In 2012, Gilman resigned from Texas' $3 billion cancer research initiative after raising concerns about not enough scrutiny of proposals before funding was approved. He had served as its chief scientific officer.