PTEN and neoplasm: Sampling of livers from mice of all genotypes at different ages revealed that loss of both Rps6 and Pten accelerated tumor development relative to each of the parental strains to the extent that 50% of ΔS6:ΔPTEN livers had developed at least 1 tumor by ~20 weeks age (Fig 6C) with 1 mouse developing tumors as early as 8 weeks of age.