(g) Model for MBd fate in cells. The newly formed MBd is preferentially inherited by the daughter cell with the older centrosome (top panel). The inherited MBd (black ring) is recognized by binding of the NBR1 autophagic receptor (grey circle) with the midbody protein CEP55 (magenta). The MBd is then encapsulated by the autophagosome (yellow circle), and degraded after fusion of autophagosome and lysosome (red circle) in differentiated cells. This pathway prevents MBd accumulation. In contrast, stem cells efficiently accumulate MBds through successive divisions and evasion of NBR1-mediated autophagy. Furthermore, differentiated and stem cells possess overall high and low autophagic activity, respectively. Uncropped images of blots are shown in Supplementary Fig. S6. 