tokens: In a previous study , we found that treating transgenic Big Blue rats with the hepatocarcinogen N-hydroxy-2-acetylaminofluorene ( N-OH-AAF ) produced the same major DNA adduct in the target liver and the nontarget spleen lymphocytes and bone marrow cells , induced lacI mutants in the liver , and induced much lower frequencies of l acI and hprt mutants in spleen lymphocytes .