FOXO1 and neoplasm: Conditional deletion of this tumor suppressor gene leads to gradual depletion of quiescent MuSCs, similar to the loss of the Notch pathway effector Rbpj. Mechanistically, Pten deletion increases AKT phosphorylation, which induces cytoplasmic translocation of FOXO1 and suppression of Notch signaling since FOXO1 binds nuclear NICD and acts as co-activator [37].