PTEN and cancer: Emerging evidence indicates that, in addition to growth-promoting PI3K alterations, PTEN loss is also associated with an immunosuppressive tumour state11,47,53–55 that favours cancer progression.53,54,56,57 For instance, in a murine model of T cell acute lymphoblastic leukaemia, Pten deficiency was reported to promote cell survival in a previously unsupportive TME.58 As discussed above, PTEN loss triggers senescence as a failsafe protection mechanism against cancer onset.