HDAC2 and neoplasm: We therefore used two different approaches to investigate the direct effect of Hdac1 and Hdac2: i) the use of mice with only one allele of Hdac2 (Hdac1Δ/Δ; Hdac2Δ/+), which do not have this block in B cell development to study the tumorigenesis and ii) a transplantation approach allowing conditional deletion of Hdac1 and Hdac2 (using inducible CreERT) in existing tumor cells and test the effect of Hdac1 and Hdac2 ablation on tumor maintenance.