Scer\GAL4^neur-P72-mediated expression of Rab5^{Q88L.Scer\UAS.T:Avic\GFP-EGFP} (controlled using Scer\GAL80^ts.αTub84B) results in SOPs presenting a single Sara-positive endosome which is segregated unreliably between pIIa and pIIb: in 40% of SOPs, it is mistargeted to pIIb instead of pIIa (as in wild type). When targeted to pIIa as in wild type, SOP division leads to two cells with normal pIIa and pIIb fate. In contrast, in 67% of cases in which the Sara-positive endosome is mistargeted to pIIb, the SOP divides into two pIIa cells, and adults present cuticle phenotypes diagnostic of pIIb-to-pIIa transformation.