Total HDAC activity (red line) present in thymocytes as a function of HDAC1 and HDAC2. The genotype of the different samples is indicated on the x-axis: +, wild-type allele; Δ, deleted allele. For simplicity, the deacetylase activity function is drawn as a straight line. However, the authors determined that HDAC1 contributes to more activity than HDAC2. The outcomes observed are indicated on the right of the graph, and the speed at which lymphomagenesis develops is depicted by the double arrow in the box. Illustration by Patrick Matthias.