Asymmetric cell division is used by stem cells to create diverse cell types while self-renewing the stem cell population. Biased segregation of molecularly distinct centrosomes could provide a mechanism to maintain stem cell fate, induce cell differentiation or both. However, the molecular mechanisms generating molecular and functional asymmetric centrosomes remain incompletely understood. Here, we show that in asymmetrically dividing fly neural stem cells, protein phosphatase 4 (Pp4) is necessary for correct centrosome asymmetry establishment during mitosis, and microtubule organizing center (MTOC) maintenance in interphase. Using in vivo live-cell imaging, we show that while wild-type neural stem cells always maintain one active MTOC,