Cytoplasmic polarization of Yap1 is restored in ScribbleΔ/Δ HSC/P with expression of full-length Scribble or PDZ-containing mutants. (A) Graphical representation of the functional domains in human full-length scribble protein and the truncation mutations incorporated into an Ef1α-IRES-RFP lentivirus. (B) Immunofluorescence showing Scribble polarization and Yap1 colocalization in Lin− Sca-1+ c-kit+ (LSK) BM cells isolated from Wt mice and transduced with Ef1α-IRES-RFP (EMPTY) lentivirus or human full-length Scribble as indicated. Nuclei are counterstained with DAPI and merged images are shown in the right micrographs. Scale bar is 5 µm. (C) Immunofluorescence showing Scribble expression and Yap1 localization in LSK BM cells isolated from ScribbleΔ/Δ mice and transduced with EMPTY lentivirus, human full-length Scribble, or structure-function mutants as indicated. Nuclei are counterstained with DAPI and merged images are shown in the right micrographs. Scale bar is 5 µm. (D) Quantifications for the frequency of transduced LSK cells with nuclear Yap1 accumulation. (E) Immunofluorescence showing Scribble and pLats1 expression in LSK BM cells isolated from ScribbleΔ/Δ mice and transduced with EMPTY lentivirus or the LRR mutant. Nuclei are counterstained with DAPI and merged images are shown in the right micrographs. Scale bar is 5 µm. (F) Quantification of pLats1 colocalization with Scribble when the N-terminal portion of Scribble (LRR) is reintroduced into Scribble null LSK cells. (G) Cartoon depicting the ternary complex between Scribble, activated Last1/2, and Yap1 in the cytosol of Wt HSC. **P < .01; ***P < .001.