However, loss of Dicer greatly accelerated tumor formation in mice co-ablated of one or both functional alleles of p53, and nearly all DicerΔ/Δ, p53Δ/Δ mice presented with skin tumors by one year of age, a time point prior to formation of any tumors in p53Δ/Δ mice. This evidence concerns the gene TP53 and neoplasm.