Mass spectrometry analysis of H3K79 methylation in thymuses from 3-week-old mice, either wild-type (Cre-) or with deleted Hdac1 or Dot1L alleles, as indicated. Mean and individual data points of biological replicates; H3K79me0 is the predominant state, the y axis is truncated at 70% for readability. The remaining H3K79 methylation after homozygous Dot1L deletion is probably due to the presence of some cells in which Cre is not expressed (yet). p<0.01 (**) and p<0.001 (***) by two-way ANOVA, comparison to wild type. 