CALM-AF10 affects H3K79 methylation as a dominant-negative competitor of AF10. (A) Stable ectopic expression of AF10 in U937T cells containing CALM-AF10 restored H3K79 methylation. For each Flag-tagged expression construct, H3K79 methylation levels (left panel) after induction of the Flag-tagged proteins (right panel) were examined in 2 independent stable cell lines (denoted as a and b for each construct). (B) Mass spectrometry analysis of H3K79 methylation in total histone extracts prepared from stably transfected U937T cells with ectopic expression of AF10 or its OM-LZ deletion mutant.