The single-stem-cell transplants were performed as described previously39,40. CD45.1 recipient mice (C57BL/6J × 129S6/Sv F1, 8-to-12-weeks old) were fed with water supplemented with the antibiotic enrofloxacin (Baytril, Bayer Corporation) for seven days before irradiation and for the duration of the experiment. The lethal radiation was delivered as a split dose of 1,000 rad (500 rad each, 3 h apart) using a 137Cs GSR C1m source (GSR Gmbh).
