A U.S. scientist who assisted Haruko Obokata with what appeared to be groundbreaking stem cell research has corrected a paper she published in a U.S. magazine in 2011, citing an erroneous figure.

Charles Vacanti, a professor at Harvard Medical School and former adviser to Obokata during her research at the Riken Brain Science Institute, posted the error in the Tissue Engineering Part A magazine last Thursday.

The 2011 paper is one of several published works by Obokata that have come into question since allegations emerged that new stem cell research papers released by Riken in January — in which Obokata was lead author — contain serious errors.

The correction to the 2011 paper states that some data related to genetic function "were inadvertently duplicated or mistakenly placed" in one of the figures.

Obokata, with the help of Vacanti, was the main author of the 2011 report, which discussed the possibility that cells obtained from an organ could develop into various kinds of cell.

"The authors apologize for these errors," said the correction for the paper titled The Potential of Stem Cells in Adult Tissues Representative of the Three Germ Layers.

Vacanti, who currently belongs to Brigham and Women's Hospital, was one of the co-founders of the U.S. magazine established in 1995.

Other co-authors of the 2011 paper included researchers of Waseda University and Tokyo Women's Medical University.

The Riken papers on so-called STAP cells drew global attention after they were published in the British science journal Nature.

But Riken admitted last week that the STAP cell papers show serious aspects of malpractice.