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. This evidence concerns the gene HDAC1 and neoplasm.