In December, Nature reported on the Research Center Borstel in Germany, which was caught up in the revelation that several researchers in its immunology group had allegedly been involved in long-running scientific misconduct. Now, the case is assuming "ever-more alarming proportions," says Nature's Quirin Schiermeier. The center has announced that six more papers published by current and former members of the immunology group are being retracted, bringing the total number of retractions to 12 so far, Schiermeier says. Silvia Bulfone-Paus, who ran the group and is listed as a co-author on all 12 papers, is accusing two former postdocs — Vadim Budagian and Elena Bulanova — of manipulating PCR and western blots in multiple papers, but says she didn't know anything about it. The two postdocs have declined to sign at least one of the retractions, a 2005 paper published in the EMBO Journal.