PTEN and neoplasm: Consistent with the causal role of Pten downregulation in tumor escape of p110α-loss, tumor onset in p110α-deficient/NIC animals lacking an allele of PTEN was dramatically accelerated from 351 days (n=45) in the p110α-deficient/NIC animals to 108 days (n=18) but only modestly accelerated tumor onset as compared to wild-type NIC mice that had tumors appear at 138 days (n= 44) (figure 3a).