PTEN and lymphoma: Retrospectively, it could be surmised that the enlarged thymus observed by Guo et al. [103] contained a lymphoma since Pten loss without collaboration from OT-II-TCR can bypass β-selection and attain the DP stage Other interesting finding reported in Guo paper [103] was that rapamycin, an inhibitor of mTOR (downstream target of PI3K/AKT pathway upregulated by Pten deficiency), could not reduce (and therefore inactivate) P-S6 level of the LSC subpopulation whereas it reduced P-S6 level of CD3+ blasts.