Numb is also mislocalized in cells that express a nonphosphorylatable mutant of lethal (2) giant larvae (LGL), which is a substrate for atypical protein kinase C (aPKC) — a protein of the ...

One explanation for the difference in spindle orientation between pI and pIIb/neuroblast cell types is that pI does not express Insc, and thus cannot respond to the apical PAR-3–PAR-6–aPKC cue.