HDAC2 and neoplasm: Eμ-myc mice with a single allele of Hdac2 and no Hdac1 (Hdac1Δ/Δ; Hdac2Δ/+), but not with a single allele of Hdac1 in absence of Hdac2 (Hdac1+/Δ; Hdac2Δ/Δ), exhibited delayed tumor development (Fig. 2).