Lgl PB domain is essential for its PM targeting and functions in Drosophila. (A) Subcellular localization of Lgl^ΔPB::GFP (ΔPB) and Lgl^KR12A::GFP (KR12A; all lysines and arginines mutated to alanine) in Drosophila follicular cells (n = 8 each). Cells homozygous of lgl^ΔPB::GFP or lgl^KR12A::GFP were labeled by the loss of RFP. (B) Residual PM targeting of Lgl^KR12A::GFP is also reversibly inhibited under hypoxia in follicular epithelial cells. Loss of RFP marks lgl^KR12A::GFP clones, whereas wild-type lgl::GFP twin clones are labeled by increased expression of RFP (indicated by white asterisks). (C) Follicular cell clones of Lgl^ΔPB::GFP (ΔPB) or Lgl^KR12A::GFP (KR12A) show overproliferation and loss of polarity. Polarity protein dPatj (red) localizes to the apical side in wild-type follicular cells but is mislocalized in lgl^ΔPB::GFP or lgl^KR12A::GFP mutant cells (labeled by the loss of GFP; blue), which also become multilayered. White boxes in the right of most panels highlight the area enlarged in the left panels. ***, P < 0.001. Bars, 5 µm. Error bars represent means ± SEM.